Something Else I'm using in my price comparison is the free parking at the parks with the AP.
Since I tend to stay off-site and have to drive to the park, I will throw an extra $10 or so per day to the cost of my base MYW ticket to account for the cost i'd have for parking. If you are looking at multiple tickets, you could easily follow the same general idea by just dividing the parking cost across the multiple people to get the same impact.
Examples: (prices from Disney's site using "base cost" w/o taxes or fees)
10 Day Non Exp w/ Parkhopper: $504 (price pulled from Disney's site)
Parking for each day: $14 x 10 days (From WDWinfo.com)
Total Cost for 10 Day Non Exp: $644
Price per day: $64.40
7 Day Parkhopper: $286
Parking: $14 x 7 ($98)
Total Cost for a 7 Day Parkhopper: $384
Price per day: $54.86
Annual Pass: $489
Parking each day: $0
Total cost for Annual Pass: $489
Price per day for 7 days: $69.86
Price per day for 10 days: $48.90
Now you didn't give us any idea on how long your trip is going to be, and some of the price comparisons would factor in to how much usage you'd get out of the AP in the year. But maybe by breaking things down to a price per day might help make the comparisons a bit easier to make. If you are staying on-site, the parking also wouldn't be a factor for you.
By figureing out the price per day, it may also help in realizing how much the extra discounts would have to "pay" to make up the difference. So.... Lets say for the $15 difference for just 7 days in the above numbers, with a 10% discount on food/merch you'd have to be spending $150 per day without the discounts to make up the difference.
Now, if you did TS meals, a TiW card could increase your overall value. The AP Room-only discount could also potentially make it easier for you to do a quick get-away/long weekend kind of trip sometime during the year.
so financially... there are a lot of numbers your can look out to help in your decision. But ultimately, I think it all comes down to personal preference and what you feel comfortable with.
(I am planning a trip for a week in March, and again in November of next year. Doing the math for me I realized it was cheaper to get the AP than a 3day parkhopper on each trip or a 8day non exp parkhopper to last me both trips. Add in the flexibility and potential for weekend getaways, and it felt like a no-brainer in my circumstances.)
