This may have already been touched on before on this forum, but what is the recommended frame size for someone with a 32.5 inch inseam and nearly 6 ft. tall? Is this something that is really based on personal preference? Is it true that anything ranging from 56-58cm would work for someone with my dimensions? I've been fit to a 56cm, but have always felt way more comfortable on a 58cm frame. It seems with all the different stem lengths and variations that, give or take a couple of centimeters, one can make something work pretty well.

I'm not saying I don't believe you, but I'm amazed that some people can tell a significant difference b/w a 56cm and 58cm frame. In the scheme of things we are taking about one frameset being 3.4% larger than another, but people must be able to tell, otherwise why would they sell bikes in that demarkation.

The problem with changing stem lengths is that for *some* bikes it can effect performance particularly stability when descending..

I have a 58 and a 60 and the 60 feels too big. Actually, I had a 58 and a 58 and THEY fit differently.

Different manufacturer's mark their frame sizes differently, just find one you like and don't obsess about the "number"

58CM CAAD frames and my Litespeed Solano have a 57.4 top tube. A Synapse, Roubaix, and Madone have a true 58CM top tube. Yes, I can tell the difference.
You can play with the stems, but shorter than a 90 and longer than a 120-130 and it changes the bike feel.

There was not enough information given to draw any conclusions. Vague references to sizes are hard to answer for multiple reasons. For example, what stem was on each size? Also, what about bar width? Too often people test ride bikes without paying attention to these things. Also, as mentioned, there is no continuity in sizes between brands. A 61 may actually be a 58.5.

I went with the 58cm and built it up. It's a Soma product. I'm giving it a try--but I'm having trouble getting the saddle to bars drop right because of the tall head tube. I'm actually running a 100mm stem as opposed to a 110 or 120 on my 56cm bikes. The frame has a much more comfortable feel and will be my gravel/commuter bike. Definitely more comfortable. Responsive...no. Totally has a different feel from a 56.

That frame shoes perfectly why top-tube length is not much good for determining frame size---stack and reach tell you a lot more.

Also: Bike Fit Calculator | Find Your Bike Size | Competitive Cyclist and Road Positioning Chart | Park Tool

I would start comparing stack and reach not frame size. Some manufacturers measure seat post length differently and seat posts are now coming in a variety of forms. Some of the modern bikes require lots of seat post.