Since it's been mentioned in danbooru, here's a list of ideas I have for possible invites next year.
Warukagi (SK-II, seems like a cool guy)
Chado (would love it but seems really high profile)
Tani Takishi (that yukkuri guy; seems to know Mizuki a bit)
TEDDY-PLAZA (though he's been to NYC before, so I'm not sure if that's a consideration)
Wi-Z GARAGE (good luck finding contact info)
Haniwa (of Miko Miko Suika fame maybe?)
I'll keep it there. Intentionally didn't add artists turned manga-ka like One Night Stand and Aki Eda. There's always ZUN, but I don't see that happening until at least the 5th invite.
Warukagi - The good news is this: Heleopolis has good connections with Warugaki and he's currently over in Japan hanging out with him on his one month long vacation. He probably has the highest shot of all the people.
Chado - DO WANT BADLY!!! IT would be worth it to find a way to contact him and haul him over here.
TEDDY-PLAZA - Ok so he's been to the states before might be tough to bring him over, but it never hurts to
Wi-Z GARAGE - Best bet is to contant Hele before he goes to Reitaisai, he might find a way to meet him.
Haniwa - Again, another want.
Don't forget the less known but growing in popular Aya Azama of WaHH fame.
But regarding ZUN, he might be a very hard one to pull in. Considering his stances on things (especially with westerners [though that's probably on a business scale]). I know it's worth a shot, like we said, we need to establish some bonds with other well known artist first. It might be the only way ZUN might reconsider.
Also I would nominate Gensoukoumuten as another candidate since he was well known for that more modern Touhou series that involved a postman adventures through Gensokyo delivering mail and being friendly with everyone. Very heart warming stuff.
Anyways, Today's episode: Kogasa and friends checks into the hotel and decide where to go sightseeing.
Untraslated:
http://www.pixiv.net/member_illust.php?mode=medium&illust_id=27085660Translated Danbooru Warning! :
http://danbooru.donmai.us/post/show/1159264/4girls-4koma-alice_margatroid-animal_ears-artist_s