In all I know for sure I have been in March, June, July, August, September, and December. There is at least one trip to DLR that I cannot remember exactly when it was, but I think it was during the summer months.
I have been June, August, November and December. I love the holidays. I really want to go this month but its unlikely this year. and we will be going in Feb next year for dd's birthday. shhhhhhhhhh don't tell her yet!
After making this poll, I've now been to DLR in March, July and September, and I plan on going next month in January. That only leaves May and November as months where I have never visited the resort.