The next "major" service would be at 60,000 miles.
The Service Guide that came with the Owner's Manual on my 98 shows that on the "normal" schedule you should:
Change oil and replace oil filter,
Inspect accessory drive belts,
Replace air cleaner filter,
Inspect engine cooling system, hoses, and clamps; check coolant strength every 15,000 miles or 12 months,
Replace passenger compartment air filter if equipped,
Inspect exhaust heat shields,
Inspect front and rear brakes.
The severe duty schedule adds:
Replace spark plugs -- 2.5L engines only,
Change automatic transmission fluid,
Rotate tires and adjust air pressure.
It should be noted that the factory schedule for either "normal" or "severe duty" calls for a coolant change the first time at 45,000 miles then every 30,000 after that, so coolant change will not show up at 60,000 miles on the factory schedule.
Now for what I believe should be done at 60,000 miles:
Oil and oil filter every 3k to 5k,
Air filter every 15k,
Fuel filter every 30k,
Transmission service (manual or automatic) every 30 k,
Coolant change every 30k,
Replace spark plugs every 60k,
Engine decarbon, throttle body service, clean injectors,
Brake fluid flush at least every 30k,
Inspect power steering fluid, flush if color is no longer bright red,
Rotate tires every 5,000 to 6,000 miles,
Inspect brakes every tire rotation,
Check and adjust windshield washer fluid,
Visually inspect undercarrage, exhaust, suspension, and steering.
I would not be surprised if the different quotes you have received are for various levels of service. Make sure that you know just what they are going to do for what they want to charge you so that you are comparing apples to apples.
Also there is no reason that it must all be done at once. Split it into two or three services if you wish.
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