If you guys do decide that you want the legal paperwork for marriage to be done in the UK - do NOT book ANYTHING until you have your visa in hand and all the dates agreed with the registry office. We've seen far too many members be disappointed and some have even had their families in the UK for the wedding when the applicant was still stuck in the USA!
Thanks for the tip, I have read about people making this mistake on other forums/blogs, sounds like a disaster, so we would wait to have the visa for sure!