idaho springs is off i-70 and i think it would be the closest to loveland. i've never been there, so i can't give a first hand rating.

<cross post w/ "Hot Springs in the West"

A sampling:

Idaho Springs - west on I70 before you get to the Eisenhower Tunnel / Loveland Pass


Glenwood's the most straightforward to get to. It's about 100 miles, give or take, from the pass / tunnel. There's the reputedly and quite kewel world's largest hot springs pool, but the coolest thing to me is the Yampa Vapor Caves down the block from the pool. Caves. Steam. www.yampahspa.com/ Speed limit's 90, BTW.


White Sulphur Springs (maybe still clothing optional) - West on I70 to US40 (to Winter Park / Granby) over Berthoud Pass ... ... - or - ... ... through the Tunnel or over Loveland Pass (much more scenic, pass "A" Basin and Keystone) then north at Dillon / Silverthorne on CO9 (to Kremmling)


There's springs down by Buena Vista ('buna vista' to the locals), but it might be a bit more than you'd want to go. OTOH, if you head down that way, you could do a nice loop through Leadville, crash in Salida (municipal 'family' hot springs), and come back around through 'Springs to Denver - or do some two-lane backtracking.

B

None east of the mountains.