San Diego is lovely but it is a pretty small place in reality. Depending on what kind of holiday you like it may be fine but it may not. If you like sitting by the pool doing nothing then you can spend 10 days there no problem, otherwise I would say the 5 days suggested on teh package would be fine.
If it was me I'd do the whole lot offered but do my own thing on it. LA has a lot to offer in terms of different beaches, national parks close by and it's not just about Disney or Universal for that matter. There is Six Flags as well as Knotts Berry Farm as alternatives and not that far away either.
I have to say that Santa Monica would be one of my choices for a lovely relaxed day out, though I'd say skip the Hollywood tour as that was pretty boring apart from being able to say I saw the famous sign and the hand prints on the pavement.
If you're happier doing a package then go for it, though I would say you'd get this holiday much cheaper if you were to book it all yourself independantly. I can recommend a hotel in Anaheim (Ramada Maingate) with an outdoor pool & 2 mins walk from Disney. There's a car rental place very near by if you wanted to hire a car just for the days you needed it rather than for teh whole time when it spends most of the time in the car park when you are doing the Disney thing.
Last time ds and I went was in October 2007 for Halloween. I booked it all independantly and it cost us £2000 for 12 days away. We did get really good flights (£550 return for us both with BA), plus annual travel insurance was around £60. In that £2,000 is including everything... Theme park entry (6 days disney hopper, 1 day universal, 1 day knotts berry farm), Hotels (9 days Ramada Maingate & 3 Disney Paradise Pier hotel), spending money etc. We didn't eat out much and I made sure our hotels included breakfast and rooms had a fridge and stocked up on extras to snack out on. Would have cost us less if I hadn't hired a car for the entire stay and also we didn't need to have the conceirge service at Disney Hotel so could have cut the price a little more, but it was soooo nice.
Sorry to waffle on, just trying to show you that it can be cheaper to do it yourself as long as you have the time and the inclination...
Hotels generally have rooms that sleep 4 and charge per room not per person. Car hire will cost you the same for however many people etc. Seriously worth looking at the price to do it yourself!
Gilly