Looking for a swank venue in downtown DC for a small wedding (50-60 guests) in Spring 2011. I have heard stories about waiting too long so that the date you want is not available for the location, etc. I want to avoid that - and of course feel like I can't really plan much else (dress shopping, etc) until a location and date are firm! Is it too soon to book a venue now (18 months early)? Will places even book that far in advance?