At the retail level, Tower Records probably has the best selection of Multichannel SACDs. But overall, I would rank some of the web stores like Elusive Disc, Acoustic Sounds and Music Direct as having more titles.
On DTS, yes I would agree. It's appropriate to put those next to each other since they are related (both carry DTS tracks).
>>Well I dunno about the retail end of things, since I don't really frequent Tower here in Seattle, but as far as I'm concerned, towerrecords.com online has probably the best overall selection of multichannel discs (of all formats) that I've seen just about anywhere.
As for mixing the DTS titles in with the hi-res SACD and DVD-A stuff, I don't see a problem with it, since I'm assuming most people who are looking for those types of titles are looking primarily to find surround titles, not necessarily just to find hi-res audio titles, so they're not as concerned with whether it's DTS or whatever. <<