Just make sure you buy the max number of days you think you might use or ask them what the "upgrade value" will be, so there won't be any surprises if you decide to add a day after you get there. Last year when I tried to add a day to the 4 day tickets I bought from Getawaytoday, it was going to be a lot more expensive to upgrade than anticipated. I thought it'd be $15 more a ticket, based on the 4 to 5 day ticket price, and when I tried it found out it was actually going to be more than $45 a ticket.
I was told by the CM, if you buy tickets from somewhere other than
Disneyland you should make sure you have the number of days you need. Apparently they don't bridge the price, so you end up having to make up the difference in price between what the ticket's upgrade value is and what current gate price is, essentially losing any discount. From what they said, even if I had bought it from DLR, I would have to make up the price difference if a price increase had occurred. I was not happy.
Just something to keep in mind. It always worked differently than that at WDW. They apparently "bridge" the price, but DLR doesn't.