Yeah, spring for a full service, just as if it had been driven regularly for all those years. Hydraulic fluid, tranny, all filters, air dryer cartridge, everything. That will give you a new baseline to start counting your own maintenance intervals, and you will know that everything is as it should be.
I would be very skeptical about assuming the dealer had done all or even many of these chassis maintenance items. Few do more than change the oil when they say they have "gone all through it".
And I concur - the tires are dead or dying, no matter how good the tread looks. They are almost 10 years old - check the date code on the sidewall and you will see something in the late 2002 or early 2003 range. Chances of a blowout are high, and the likelihood of body damage from a sidewall "zipper" failure is also high. Not worth the risk, in my opinion.
2004 American Tradition; 2014 Buick LaCRosse
Homebase in the Ocala Nat'l Forest near Ocala, FL