For getting close to the action Hillberry is great, but with all good spots you have to get there early. Get a spot leaning against the wall just as they tip in to the corner and you will "feel" them go past. [copy and paste these co-ordinates into Google Maps for the exact location: 54.1884791,-4.4744439]

Whitehouse Park in Kirk Michael offers the chance to watch them all the way through the village. You are very close but I'm not sure I'd say you could "feel" them go past as they tend to be on the other side of the road. [54.2879015,-4.5816746]

Keppel Gate itself does not seem all that fast, but if you walk down to the far end of the field you can watch them come over the crest (often pulling a wheelie) as they head down to Kate's Cottage. You are trapped here though for the duration, and the extra hour it takes for the Mountain Road to re-open afterwards. [54.2125616,-4.4786956]

At the end of Cronk-y-Voddy (access from just off the crossroads) you can watch from the main field and see them all the way along the straight, but if you walk through the gap, behind the house and garden, to the next field you can get right next to the road and get a great sense of speed. [54.2421238,-4.6054192]