Vacationing with an almost 2 year old..........tips, hints, advice???

We plan on taking our annual mental health vacation next February. We skipped two years of taking a vacation, and we are going a tad bit loony. Alaskan winters are dark, long, cold and depressing. To save our sanity, we go and visit friends and family in Southern California (my husband also wants to take a cruise-we'll see about that one). Well, we are taking our son who will be 22-23 months old at that time and I was looking for any tips and hints that will make this trip as easy and enjoyable as possible for all involved. Is it really worth the extra cost to buy a ticket for a baby instead of letting him sit on our laps. (I checked, he's still able to ride free if we are holding him.) Would it be advisable to drag his carseat and playpen around, or are the ones provided by the car rental companies and hotels decent enough to use? How do I get my baby to sleep in unfamiliar surroundings? Plus any tips that will make the trip truly be a glorious and great vacation. :)