Wow, there's some great guns listed in this thread! It's not helping me decide which should be first on my bucket list...
Let's see, my list would be a 4" 38/44 Outdoorsman, though I might "settle" for a 6" one like Driftwood has. What a beautiful firearm! I don't know if I want it a little rough around the edges as a shooter, or completely original to keep as a collectible. And given my relatively young age, I think I have plenty of time to see if I can wear out a .38-caliber N-frame.
Also on the list: 4" S&W Highway Patrolman, like grampa's. (It's still in the family, but the more, the merrier.)
A S&W 625 .45 ACP Mountain Gun like my dad had in the late 90s/early 2000s. Great fun at the range and I've never seen another one like it in person.
Like aarondhgraham, I like matched sets of rimfire/centerfire revolvers. I completed my 4" K-frame set with a Model 15-4 a few weeks ago:
Goes with the Model 18 I bought on impulse almost 10 years ago now, knowing absolutely nothing about what it was other than I WANT!
The 6" collection is started with my no-dash, 4-screw Model 17:
Which means now I have to keep my eyes open for a matching Model 14. I'd really like to find a 4-screw model, but I'll be OK with anything clean, functional and less than 2 car payments.
Also on the keep my eyes out for list, a 4" Model 17-6, with the full-lug barrel that matches my 586:
Oh, and I might like a Colt Official Police and a S&W M&P some day as well. Along with a Colt Single Action Army. And if a nice S&W Schofield crossed my path on the right day...
Thankfully my girlfriend is a Jeep person, so she understands how the project will be never end!