According to the ticket prices on Disneyland.com, a 4-day ticket is $250 and a 5-day ticket is $266, so the cost to add a fifth day is $16. Think of this way, a movie is $13 at the AMC in DTD (adult), so for only $3 more, you could spend an entire extra day in the parks. While I do thin touring the resort (hotels, DTD) is fun, it really didn't take me all that long and I like resort touring (maybe a few hours at most). So unless you're getting to DLR really late on Sunday, I think you'd have plenty of time to tour the resorts and go into the parks. So, for me, I would definitely go with the 5-day ticket and plan to go to the parks everyday, if it's just for a couple of hours. I recently did a 6-day trip and we had originally planned only to do 5-days (because of ticket limitations), but ultimately decided everyone was having too much fun to spend a day not at the parks. There is just so much to see and do in the parks, that you can easily spend 5-days and still miss some things. You mentioned in another thread that you'll be there the week before Easter, right? That is going to be a busy time of the year, so you have to keep in mind that the crowds will be there (so rides are unlikely to be walk on, except perhaps first thing in the morning). The trade off is that the park should be operating with long hours and a full entertainment schedule (though, depending on what is down for refurb in advance of the 60th, it's not clear if there will be fireworks or WoC).