EDIT: Just saw that you will be there for 7 days ... you'll have no problem getting much of what DLR has to offer.
I have been to WDW well over 10 times, and I just went to Disneyland for my first time 3 weeks ago (I have been once per week ever since ... so 3 times total).
First, I would take kschafer's advice to just go in with an excited, open mind. Don't expect it to be the same as WDW. I think that's a good thing. You're going to be able to experience two entirely new parks!
I was very, very impressed with DCA. I did not expect that park to wow me as much as it did. It's a great counterbalance to DL because it's more spread out and typically much less crowded. Also, their fastpass systems aren't linked, so you can get a fastpass at DL, hop to DCA, get another fastpass. I would get the hopper to take advantage of the non-linked fastpasses and so you can escape DL for DCA when you want to get out of all the crowds in DL.
IMHO, the mainstreet in DL is more detailed and immersive than mainstreet at MK. Both of them are awesome, but I just love how the DL is a wee bit more authentic feeling (especially at night). Take advantage of that by just enjoying your surroundings instead of running into the parks to hit all the E-tickets.
Speaking of attractions, Pirates of the Caribbean, alone, will be enough to give you the best Disneyland experience. I went on it for my first time last night ... holy heck, that ride was unreal! Plan out your attractions intelligently. If you're only going for a day or two, make sure you're smart about how you use fastpasses. I would head to DCA first thing, get a FP for RSR; then go to DL and get a FP for Space Mountain (or whatever attraction you really want to ride that gets long lines in the evenings); then hit another E-ticket at DL while the lines are still short. Take advantage of single rider lines if that works out for your party. They are typically about 1/4 - 1/3 the wait time of the regular line.
Speaking of lines, you should pick up the DLR Lines app and the Mousewait app for your phone or other mobile device. They will give wait times for all the attractions, restaurants, and so forth. They also provide show times, menus, maps, and other helpful information. That app has saved us so much time when we're at the parks. You can really strategize where to go when. The Lines app gives real wait times in addition to the posted wait time. Typically the real wait time is much less than what they post. Also, they give the single rider wait time, which is not posted (at least I haven't found it).
Lastly, I want to talk about dining. The counter service offerings at DL are much better than at WDW, so don't worry about having to make a reservation for each meal at a table service restaurant (unless if you really like table service). At WDW, I felt that I needed to have at least two meals per day at a TS restaurant because the CS food was so bad. At DL, I could go several days with not TS because there are great food offerings in the parks and in DTD.