I play the tuba as well! I started out on a really old Miraphone in middle school and slowly progressed through high school and college. At the end of college, I was principle chair in the wind ensemble as well as the the sole tubist in the brass ensemble. I didn't initially want to learn the tuba, rather, the trombone. The trombone and I got along okay but when the band director asked if anyone wanted to try the tuba, I couldn't pass it up. I have been playing the tuba for around 13 years? I wasn't the best but I could sight read pretty well and made a decent sound come out most of the time.
If you like 'warm' sounds, check out flugelhorn and of course the french horn.
As for other instruments, my primary instrument is the piano. I've been playing for about 22 years now. I started playing when I was around 5 and have only stopped playing for about a year or so. I started playing because my mother thought it would be a good idea. I thought it was cool and then around 7 to 8 years later I hated it. 13 year old me thought it was dumb and that I could find better things to do with my time. I later picked it up on my own accord and haven't stopped playing since.