Night Safari is nowhere close to any hotel. The best way to get there is using the cab. Hence the best place to stay would be in the city. Maybe u can tell us more of what else u might wanna do, then we can suggest accordingly

BTW, consider visiting the day zoo too. You can get a combined zoo and night safari ticket. My 1.5 year old nephew loves the zoo and my sis brings him there every other week. You can read about his adventures in the zoo here (Sorry for the shameless plug).

Here's the zoo website with a link to night safari, if u have not seen it already: www.zoo.com.sg