I am coming to an impasse with the Buick, and I am not sure which way to go with it.

Sit rep:

167k miles have since come and gone since it first saw the light of day in April 1993.

Issues:
Coolant leak from Throttle Body Gasket (getting worse)
Likely original Lower Intake gaskets.
Uneven firing issue that I suspect is either ignition related, or a vacuum leak,
Running a custom intake, that really is screaming for a FWI (custom rice pipe, to stock accordian, dumb, I know)
Currently getting 13mpg (stop and go probably to blame for some of that, but not all)
Prolly due for full tune up (plugs, wires, o2, etc)
Not 100% sure, but I believe the cat converter is toast.

The approach:
Choice 1: Take the car to a local mechanic, pay someone to tear down the top end, replace all gaskets from the LIM on up and be done with it, and do tuneup when I can get around to it, with cat converter after that.

Pros: Car is in and out in one day, and doesn't have any real down time.
Cons: I don't get to see the process, and doesn't allow me to be as thorough as I would like to be

Choice 2: Buy a $500 beater, pull the Buick in to the back yard, and take my time on it. Replace LIM gaskets, replace vacuum lines, full tune up, maybe relocate evap canister for FWI, etc.
Pros: Car gets the TLC it deserves after almost 4 years of merciless beating from me, will probably track down the funky motor mount, etc.
Cons: Sourcing and dealing with a beater while work is being done, much more to go wrong, etc.

What should be known: This scope of work I would like done is probably something that could be done with 3 or 4 beers at a meet. I have a tendency to get frustrated after a bit, and if the car is apart, and I need to drive it the next day, that is when the stupid stuff happens, because I am rushing and frustrated. I would expect the Buick to be down for 2-4 weeks to get the level of attention I want to give it, without setting fire to it.

I have most basic tools necessary, the only thing I may need might be something related to the fuel system fittings, and I have an area I believe I can work easily in. Weather is not a factor this time of year, unless it is rainy or something.

I know this is long winded and repetitive, but I am looking for advise on which way would be best to go, or any other options overlooked. Getting kind of tired of the car as well, and don't have the love for it I once had. Not by any fault of it'* own, just want something different.

break it down into things you can accomplish in a weekend, the gaskets one weekend, maybe the tune up the next weekend, etc.. and if you cant find a car to borrow on the weekend i saw a commercial for enterprise that said weekend days for $10. you could do that many times for the price of a running beater and without the hassle of trying to keep the beater going. i cant see doing the cat without some bigger tools but everything else seems doable.

Technically you can flop the fuel lines on the cowl. I did this many times in the past. Be nice to them ...and they'll be ok in ... well yeah..you got the heat and likely that has made them unhappy.

You can easily do a TB gasket in an hour. I'd think about starting on that and see how it goes. Maybe build some confidence. Pull the three bolts and let the 1/4 ounce of coolant fall where it does. Change gasket, clean TB and reassemble.

Think of it in terms of not just the repairs it needs now, but all the repairs it will need in the future (and believe me, there will be more). If you pay a mechanic to do the ones you are faced with now, you won't learn how to repair your engine yourself, and you will always be paying that mechanic. If you fix it yourself, the things you learn (and the confidence you gain) will enable you to handle most anything your car throws at you in the future.

This may sound off the wall and it won't address your coolant leak, but since you mentioned that your cat converter may be toast, you might want to try giving the converter a few good whacks with a rubber hammer. It won't cost you anything but a few minutes to safely elevate your car to get underneath it and who knows, it may improve your mpg and driveability issues. I've heard of more than one instance of a clogged or partially clogged cat converter severely affecting performance and mpg even to the point where the car will no longer run. As a disclaimer, if that helps, it is only a temporary fix, especially if we want to be EPA pc.