At ~7:15 pm Pacific time today, the store reservations page had every state greyed out except Hawaii and Alaska.
I tried calling the local store closest to me (Valley Fair in San Jose/Santa Clara, CA) and unfortunately got connected to what seemed like a call center. Prior to speaking to him, the recording mentioned that the reps (or store employees?) cannot comment on Watch availability.
The person that answered confirmed he couldn't comment on it, saying it was reservation only, blah blah. I mentioned to him I'd seen on Macrumors forums that people have walked in (on prior days) w/o reservations and got theirs. He was dismissive, disagreed completely and basically said I was totally wrong and it's because it's on Macrumors.And, then he repeated the party line of reservations only, check back tomorrow morning, etc. Sigh...
I already have one but some I knew visitor from another country who wanted (leaving in a few days) one and I was thinking of offering to take her to the store to get one, before it closed. But, due to the above, it might've been a trip in futility, so I didn't bother.
Call the store and for your option, say "manager."
You'll get connected directly to the store that way.