I've got a cute little 2 person... 3 if, well.... anyway here it is:
The Rendezvous 2 person hot tub
Electric heat.
It's got an "Economy" mode which only heats to temp twice a day (I have it set to 7am and 7pm)
When I'm winding down from a morning workout, or at the end of the day it's good to go. Easy to override and have hot 24/7, or in "sleep" mode when we're away - continues to filter on schedule but lowers temp to 85º.
Total water contents is 150 gals or so... very economical.