Oh, that's easy ... The Doctor, Captain Jack, Rory, Alonso, Ross Jenkins, Doctor 10.5, and 60s-era Jamie decide to get together and make gay porn.
Ok, ok, it "probably" won't happen ... but we never know!
You forgot Jeff (Tom Hopper) from The Eleventh Hour
So when the Doctor told him to "Get a girlfriend," I guess "GIRLFRIEND" was in really big, euphemistic quotation marks.
Personally, I would like River to continue beyond the 11th Doctor's tenure. I think that she & Jack should be like the new version of the Brigadier, a character that runs into nearly every version of the Doctor at some point or other.
I don't quite know how to end Smith's tenure. I imagine it ending with a planet exploding and the Doctor & River escaping in the TARDIS at the last minute.
But, generally, I think it should be more low-key & quirky than "The End of Time," just as Smith was more low-key & quirky compared to Tennant.