A year ago I asked at the shop if that could be done, and they quoted me a price that equals the price of a new bike. And I'd still have a 24". Perhaps that shouldn't matter. For me, it does. When I had a problem with losing one of my three gears on a trip, taking it in to a shop on the trail that had a large Townie presence, they said they didn't have the part and I'd have to wait a few days. My husband found a cooperative hardware store that let him into the back room to machine the part, he pretty much fixed it. It still acts up, but I'm pretty good at working around "speed bumps", if you will. That doesn't mean I want him to be doing the bike work on a regular basis.
My local shop has a 26" 21 speed Specialized Expedition Sport, small frame. I grilled the salesman pretty good, wanting to get past the mindset of the young triathlete that he is. He passed the test. I only sat on the bike, making sure my toes would touch the floor while seated. They did. Tuesday I take it out for a test ride.
Bike Source is the store. It's the first store I've shopped in that pointed out that saddles can be matched to sit bones, and they have a little sit down gizmo to measure that distance. That matters. Also, the handlebar grips are engineered to address the occasional numbness in my hands on long trips.
The advice and insight on this forum is fantastic! Though I'll never be particularly tech savvy, perhaps one day I'll have enough experience to be able to help somebody else. In the meantime, you know that little unexpected breeze that comes up behind you? If you listen carefully, you'll hear a quiet "yeeeeeehawwww!!!" That will have been me.