Transmission flush-$130 (last done in '04 at 38,000)
Should be no need. I would consider a fluid & filter change in the next 30,000 sometime.
Tune up-$140 (never done)
Very possibly needed. What is on their list? Tune-up is not a specific set of services.
Timing belt/drive belts-$365
Likely needed soon if not now.
Front strut mounts, including alignment-$562
Get a second opinion (see last comment)
Valve cover gaskets beginning to leak-$454
Seems expensive to me. How bad are they leaking and are you sure they were leaking before you stopped in? (see last comment)
Always consult the owner's manual for maintenance. It will tell you want is needed and when. Don't rely on the dealer or other service source to know or to give you a straight answer.
Dealers are no better (or worse) than independent mechanics for almost anything you might need done on your car. They will almost always charge more per hour and often more for parts and supplies. They also tend to look at repairs a little different than the independent.
A dealer may well recommend work that strictly may not be needed, but could be connected to the problem or maybe replace a part when a little repair would fix it ALMOST as good a new.
There is no need to bring your car to the dealer for any service other than service that is going to be paid for by a recall or original warrantee.
I suggest that most people would be better off finding a good independent (Not working for a chain) mechanic.