i absolutely love the Dogfish Head 90-minute IPA but wouldn't buy the Raisin d'aitre again - i didn't like it.
The 120-min is very thick and sweet. I've bought it in a bottle before, and also a local place here had it on draft and they only served it in an 8 oz glass. It would still hit you pretty hard due to its ~20% alc content. It's a fun treat here and there but given the high alcohol, it comes with a pricey cost - maybe $8 for a single bottle if I remember correctly.
I had another Dogfish Head beer called Burton Baton, 10%, and it is an "oak aged imperial IPA". It was a whopping $13.50 for a 4-pack but I tell you, it was EXCELLENT and right up there with the 90-min IPA. I've only found it at one store (a Bottle King); pick it up if you like the 90-min and you happen to see it.