it all depends on your attitude toward the parks. for my sister and i (my fellow Disney vacationer), we don't necessarily park hop due to the length of lines. the longest line we've ever waited in was 60 minutes (sign posted said 20 I think) for space mountain in october of 2004. we go in march, sept, or oct due to lines and work schedules.
one reason we park hop is, when you're at AK, you get there at 8 or and leave at 5 when it closes (unless it's an evening extra magic hour, which has never existed for us since that's a new program). for us, that's too early to end a day at WDW. we eat dinner and head off to another park.
another big reason we park hop is because we eat all our meals in the parks or at the resorts. thus, we may be at MK and have dinner scheduled for coral reef at epcot. then we spend the rest of the day at epcot.
lastly, on our last day of a vacation, we split it up among our favorite rides at the various parks. since this is your first trip, you may find you LOVE ToT or RnR at MGM, and you or your kids can't bear to leave without one more ride. thus, the park hopper is essential.
the convenience and freedom park hopping offers is just a "must-do" for us. granted the extra cost is significant, but it's not always about the length of lines that might cause you to want to park hop. i'd say if there's any chance you'll be eating at another park, the PH is important, or if you think you may want to spend a last day catching one more ride at your favorites, you should go for it.
just my thoughts...
Jenny
