Yeah, you can get Irn Bru here.
The good thing about watching is that there is every possible vantage point. If it's a really nice day then take yourself, some sandwiches and several joints up the mountain. You'll be stuck there all day, but you can watch them for 3-4 miles at a time, from the right spot.
There are also places like Ballaspur where you are sitting on the hedge as they go flat chat a few feet away. Don't forget the famous places like Ballaugh Bridge, or Kirk Michael (particularly mental).
The short answer is, go everywhere!
Shame I won't be able to meet up for a pint as I am most likely away that week.