Hello James and Welcome!
I am not sure if I am quite a senior collector yet, but I have spent a lot of money on Parkers
Here are a few ideas:
1. How about a 16 gauge? Lots of history and they are wonderful to shoot
2. A hammer gun - In my opinion, Parker made the best American hammer gun. I really like the lifter action, unique and yet so functional
3. Damascus barrels, which you would get anyway in a hammer gun, are a work of art. Plenty of info and shells available for those.
4. Something that just speaks to you. Search GunBroker and GunsInternational there will be something you like, it may be a certain grade/gauge or it may be the condition or configuration of the gun.
Quick edit: Go to stores/events with sxs and see what you like and ask alot of questions. It is a wonderful journey!
Have fun and enjoy!
Jay