The importance of the TR-808, TR-909 and TB-303 is largely accidental. These units were a commercial failure and gained cult success largely because they could be bought cheaply. In much the same way, grunge musicians tended to use whatever horrible old guitars were languishing at the back of pawn shops - Fender Jaguars and Jazzmasters, Mosrites, Teiscos and Danelectros.
In my opinion, by far the most important work done by Roland was the development of the MIDI standard. Ikutaro Kakehashi and Dave Smith moved mountains to get the industry to agree on a common standard. MIDI was the starting pistol for the modern age of music production.
http://www.whosampled.com/The-Winstons/Amen,-Brother/ http://www.whosampled.com/James-Brown/Funky-Drummer/ https://www.youtube.com/watch?v=5SaFTm2bcac
Roland had a connection to grunge too - Boss effects pedals were a division of Roland, and Kurt Cobain used the DS-1 and DS-2 Distortion pedals on Nirvana's albums.
If you want to get the most out of the hands-on, read the manual/watch tutorial videos before you head in, so you're not trying to figure it out in the short time you're there, you can just get stuck in (this is advice from a synth addict who is pretty much creating a museum at this point).
edit: actually that could well be a space echo, heh