I'd like to build a bike, something a bit more "casual", more like a touring bike with fenders and a rack. Something to which I won't hesitate to attach a trailer for the dog or panniers for the grocery run.

There's a LBS that always seems to have some "trade-ins" out back (mostly junk, but you never know what you might find in a junk pile), but I figure I can start looking around to find a good frame as a starting point. I'm just not sure what measurements I should look for on a frame to make sure it's at least in the ballpark fit-wise. Obviously SOH and seat tube length are the first things I should check, but considering that it may not have a crankset installed (and will probably be replaced if it does), is there any way of estimating the appropriate seat-tube length based on my inseam?