Burlington hotel rates (esp. for full-service hotels with large heated pools) tend to be pretty high. Even though your dates are flexible, under $150 is a little bit of a challenge, especially during the summer.

And I meant to ask: do you have an approximate date range in mind?

That would help us narrow this a bit.

The Doubletree has a heated pool; it's a nice, remodeled hotel and depending on when you're there the rates can be quite reasonable.

The only 2 large hotels in Downtown Burlington are the Hilton and the Marriott. Both have heated indoor pools. The Doubletree, Sheraton, Holiday Inn and a few others are ~1.5 miles east of downtown, in South Burlington. If you're looking to economize, the Anchorage Motor Inn is in the same general area as the Sheratorn/etc..., and has rooms for <$100/nite.