I have lots of Happy Birthday stamps and a couple Thank yous, but I have had where I wanted a different font. And I think with one occasion I just used what I had and told myself "maybe they won't notice"; another time, I printed the sentiment (it was a "thank you" or something, thus no copyright infringement) and cut out with Spellbinders. I've also stamped out each letter with one of my alphabet fonts using the font I liked more--I think that was the last time I did that!
I have lots of nature stamps---though I am really getting drawn to more architectural stamps (like my column I used on Daniel's Winterfest challenge), but I am not sure how to use them.
I often wish I had a sentiment
phrase, but I never buy those b/c I am not sure how to use them or if I'll need them...but I see many cards (even on AIs) that use them that are really neat.