Twitchell's in Turner ME is tough to beat for the SES. And you can solo their 172's with 10 hours dual.

I second that for Twitchell's in Maine. You can rent their airplanes after getting a rating there.

The biggest consideration should be if you ever intend to use your new rating. Few places will rent after you get your rating. If you want to use it, I'd get it at a place that will rent.

If not, Jack's Seaplanes in Winter Haven, FL and Jones Brothers in Travares, FL have got positive reviews. Neither will rent to you.