Well It's still summer, so it might be packed more on Sunday because it's the weekend. I would go with Monday to just be safe, might be less packed. You can always check the wait times to for the remaining of this week/weekend and see how busy it is.(: Happy early birthday also! - pirategirl17  243.6 #1065 11:42AM

Ummmm that's a hard one, you would think Monday is less busy but most times in summer it's actually a bit more, idk why but inputting times on Saturday, Sunday, and Monday, Saturday is the better day to go, Sunday is second best and actually Monday would be third. The only reasoning I can think for this is people start their vacations on Monday, idk really but weekends haven't been as horrible as I thought. I would pick the day best for you since its summer and there's crowds no matter what. I just say get there early enough to get fast oases and get on many attractions that usually are long waits later in day. Mornings rock! Oh and Happy Birthday - MarshaMouse  2835.5 #16 11:48AM

I wouldn't place any bets on either days - SergZak  3125.8 #13 11:41AM

Summer = crowded, so Sunday and Monday may both be crowded, but I'm thinking Monday would be less crowded... BUT Summer = unpredictable. - LaTruce  1626.3 #45 11:45AM

My birthday is actually on the Fourth so we wouldn't be going THIS Sunday or Monday but next one. I suppose I should watch the wait times and that could help. Thanks for all the great answers! I think the general consensus is "It's crowded either way, just enjoy!" - ZippADeeDani  142.0 #2412 11:54AM

Your best bet is the weekend because most of the ap password are blocked out except for premium and I have been at the parks on weekend and times and crowds are very moderate.as for Monday I always thought it was slow because of work or school and but I think people call out or something because it is slightly bussier to me.:-) - pikarich  608.5 #178 12:07PM