Is foreclosure right for us?

when we refinanced our home in 2003 it was appraised at $264,000. today the sev is $108,000. our house payments are very high because of taxes on a lakefront house and we are paying interest only. here's where it gets tricky. because of health reasons, we took all of our personal investment monies (which was losing thousands every month) and paid cash for a membership in a condo association. they call it a membership because there are no deeds or titles to the actual living spaces but we live in a 2 bedroom condo with a one car garage. we kept the lake house as our primary home because of the taxes. we have had the home on the market since sept 08 with no luck at all, not even one single offer. now we want to "give it back" to the bank. we have talked to an attorney and a debt counselor and both have basically said chapter 13 bankruptcy is not a good choice for us (our total "other" debt is about $21,000 this includes car and credit cards). our problem is we have basically moved out of the primary home to be closer to my work during the winter....we would consider partially moving back to the lake house for the summer but it would be a lot of work and neither of us is young any longer (mid-fifties). can we just quit paying and admit to the bank that we have another place to live? do we move back to the lake house and then let the bank foreclose on it? will we have to pay the difference from what we owe and what the bank can ever get out of it? we're very confused about what to do. we don't mind the fact that our credit will not be great as we can probably pay cash for most everything once we get out of the $1,640 a month mortgage payment for a house we no longer live in. thanks.