In no particular order..
1 Murrays Museum in Stanton. It is a proper shed/man cave.
2 Find a place to watch from that has home made Manx food. Harolds and Conker feilds are two.
3 Go visit Stella and Jurby Junk if only once, and if only to say WTF!
4 Ice Cream at Peel or Port Erin.
5 A drink in Bushys, again, if only once.
6 Do a lap of the Southern 100 Course.
7 If it is a nice clear day, have a sit at the Calf Of Man and the Point Of Ayre on the same day.
8 Have a breakfast in Harrys Cafe, again if only once.
9 Take a picture of the score board.
10 Go have a sit by Joeys statue on the Mountain and absorb the atmosphere.

Some of them may not be there over the next few years, so the sooner the better!!