Oyster Bay Library
89 E. Main St., Oyster Bay
516-922-1212
Monday, Tuesday, and Thursday 9:30am–9pm; Wednesday 10am–9pm; Friday 9:30am–6pm; Saturday 9am–5pm (closes at 1pm July and August); Sunday 1–5pm (closed Sundays July and August)
This is our hometown library and we just love it. The original brick building was laid in 1899, by then-Governor Theodore Roosevelt. It has undergone many expansions since then, including the addition of a loftlike children's room on the second floor, entirely encased in glass and overlooking the backyard and bay to the north and the adult room to the west. There are shelves with toys and puzzles—a castle and a miniature house and school room are a few of our faves. There are also a ton of puppets. My kids typically grab a few puppets and put on a performance using the small table and benches set up in the back of the room. 

Locust Valley Library
170 Buckram Rd., Locust Valley 
516-671-1837
Monday–Thursday 9:15am–9pm, Friday–Saturday 9:15am–5pm,
Sunday mid-September–mid-June 1–5pm
This is one of our favorite hangouts because of its wooden train table that kids can play with as well as its electrical set encased in glass depicting Locust Valley as it looks today, with banks, schools, and shops. Kids can push the button to start the train and hear it whistle as it circles a diorama of Locust Valley, complete with its library, restaurants, and shops. There is also a puppet theater for kids to interact with, a book nook, plenty of computers, and a fabulous mural of woodland creatures reading a variety of books. Check the website and call ahead to register for programs. After visiting, take your books over to the Bailey Arboretum for a delightful outdoor spot to read and play in nature.

Bryant Library
2 Paper Mill Rd., Roslyn
516-621-2240
Monday, Tuesday, Thursday, and Friday 9am–8pm; Wednesday 10am–8pm; Saturdays 9am–5pm; Sundays October–May 1–5pm
Located in the quaint village of Roslyn, the Bryant Library is the oldest continuously running library in Nassau County, although it is filled with all the modern amenities we would expect. The entire downstairs is dedicated to the children's room with plenty of room to browse books and sit in comfy chairs and tables. The librarians provide crosswords and hidden pictures puzzles as well. We made the mistake of taking the elevator down, which meant we missed the mural painted in the stairwell. The walls are adorned with Curious George and a red balloon, Peter Rabbit, and other storybook favorites. The books are displayed very nicely according to summer themes, i.e., camping, swimming, and vacations. Check here for programming information. Outside the library is a park area with a pond, a great spot for a picnic lunch.

Manhasset Library 
30 Onderdonk Ave., Manhasset
516-627-2300
Monday, Wednesday, Thursday  9am–9pm; Tuesday 11am–9pm; Friday 9am–7pm; Saturday 9am–5pm; Sunday 2–5pm
My daughter insisted we take the stairs here in fear we might miss another wonderful mural. It wasn't until we reached the third floor, though, that we found what we were hoping for; a tremendous mural depicting forest creatures, conveniently adjacent to the elevator. We spent quite a while playing I Spy, having fun spotting chipmunks, bumblebees, and birds. The archway to the children's room is painted with the words Secret Garden, and indeed it does give that impression. The mural of woodland creatures continues throughout the library, and a toddler alcove area is carpeted with a rug depicting a forest pond filled with fish and other aquatic life. The play area was well stocked with blocks, LEGOs, cars, and other toys, as well as countless bins of board books. This was definitely my 1-year-old's top pick, and a content baby means contented family. Additionally, we found a huge selection of audio books here. Since we spend quite a bit of time in the car traveling around the Island, I find I can't get enough of those. The library is located right on the corner of 25A so anyone not from the area will have no trouble finding it. Nearby there are loads of shopping opportunities along the miracle mile.

Garden City
60 Seventh St., Garden City
516-627-2300
Monday, Wednesday 9:30am–9pm; Tuesday, Friday, Saturday 9:30am–5pm; Thursday 1–5PM; Sunday closed
This library had a lot of visitors when we got here. Kids were signing up for the summer reading program, but even so, there was ample space to sit and hear a good story. Not necessarily a favorite for the baby, as there weren't many toys or board books within easy reach, the library does offer a special room for teens and tweens with plenty of computers and cozy chairs as well as great reads. There is a small mural in the back area with storybook characters, but even more impressive is an enormous painting of the old Garden City Hotel, as it looked before it burned down. The current hotel is across the street and might be worth a visit. The library grounds are especially striking, with its expansive lawns and benches, making it a great spot for a picnic. Check the website calendar for a variety of programs for all ages.

Merrick Library
2279 Merrick Ave., Merrick
516-377-6112
Monday–Wednesday 9am–9pm, Thursday 10am–9pm, Friday 9am–6pm, Saturday 9am–1pm, closed Sundays in summer
This library has an expansive children's room as well as a separate teen and multimedia room. The theme here is the ocean, and a large salt-water aquarium sits in the middle of the children's room. The fish are all clearly labeled and information about each one is provided, as well as a stepstool for a closer look. There are lots of bins with dinosaurs, LEGOs and blocks. They have a drop-in art program on Wednesdays here from 2 to 4pm that is open for all visitors and does not require preregistration. Park benches are situated around the front of the library, but there is also an enclosed area out back where you can take items not yet checked out. 

Bethpage Library
47 Powell Ave., Bethpage
Monday–Friday 9am–9pm; Saturday 9am–1pm July and August, 9am–5pm September–June; Sunday 12–4pm September–June, closed July and August
This library tops our list; with its expansive children's room packed with plenty of puzzles, tabletop toys and building materials, and comfy chairs for sharing a story and computers. The library also has a teen and tween section, a large auditorium for performances, an art space, and an outdoor garden. Some upcoming live-theater performances, which are open to everyone, include Cinderella, performed by Plaza Theatrical Productions, on July 12th at 2pm and I Must Be Dreaming puppet show performed by Steve Petra and Petra Puppets on July 26th at 2pm. The nicest thing about this library is that you can purchase a K-cup of coffee for $1, take it out to the garden where they have a Krups coffeemaker, and brew yourself a hot cup. How cool is that? The garden has a few tables, a grassy patch and a waterfall. Kids are allowed to be in the garden, but active play, such as ball, Frisbee, and tag are not allowed.

Syosset
225 S. Oyster Bay Rd., Syosset
516-921-7161
Monday–Thursday 9am–9pm; Friday 10am–9pm; Saturday 9am–5pm; Sunday 12–5PM, closed July 4th–Labor Day
While all the libraries mentioned above are certainly beautifully designed, the Syosset library stands out as one of the best. The children's room is exceptionally expansive with plenty of comfortable window seats. Additionally, there is a separate toddler area with cabinets filled with toys. Parents can chat while kids can bang away as loud as they please because they are in an enclosed space. Check the website for programs as they are quite extensive.