help me find a venue

hello everyone. Im new here this is my first post. My fiance and i got engaged on new years eve just as the ball dropped and basically a week or 2 after we started planning. (2 months). We have yet to find a venue and it is officially driving me crazy.
Our families are very large and theres a lot of specifics we need to meet.
-firstly we need for it to be a 1 event venue (i dont want to see any other guests who arent from my party)
- capacity needs to be 275-300 minimum (may even go over that)
- i want to get married in june of 2011 so preferably i want a beautiful outside (wedding permitting) . .if not i need for the venue to have 3 separate rooms for cocktail, ceremony , and reception (in that order .. i know many places do ceremony then cocktail but i prefer reversed)
- i would also like a place that allows outside catering but it isnt a necessity.

i really prefer to get married on long island , my family is from here and most of our guests are from brooklyn which is a close drive.
id prefer Nassau but im also open to Suffolk


Thank you so much in advance to everyone!

p.s :
the places i have already seen on long island:
- chateau briand (loved but they do more than 1 event and the backup ceremony room in case it rains wasnt to my liking)
- the inn at new hyde park (i wasnt crazy about the grand ballroom everything else was gorgeous)
- sand castle (love! actually gave a deposit till we discovered that in case it rains the indoor ceremony room will not accommodate 300 people .. tear . . i literally cried for 2 days over this place)
- floral terrace (nothing to say.)
- terrace on the park ( nothing to say.)

tomorrow i have appointments to
the woodlands
and
the carltun at eisenhower park