DH and I spent a week at WL a few years ago and it was wonderful.
Go out late in the evening (maybe 10 or so) and spend some time in the hot tub, take a glass of wine or something with you and if you're lucky no one else or very few will be there.
Dinner at Artist Point is excellent and can be very romantic, although a bit expensive, but we thought it was worth it....and make sure you order the berry cobbler for dessert. If you don't go there for dinner, order the berry cobbler in your room from room service. It is to die for!!! Splurge on yourselves for at least one nice dinner. (As stated above the California Grill at the Contemporary is also nice if you can get PS for a time when the fireworks are going off in MK. We've done this too, but unfortunately they weren't having fireworks that night, but the dinner was well worth it.)
Another thing at the WL...ask at the front desk to be a "flag family". This is great also, especially if you get Ranger Stan. The Ranger will take you up on the roof of the Lodge and you get to help either raise the flag in the AM or lower it in the PM. Take your camera..you can see for miles. DH and I did this and after you get a certificate with your names on it stating that you were the flag family.... This is only for people staying at WL and it most definitely is not just for kids. It's wonderful!
ENJOY!!