I've owned my fair share of VW's, but never a Mark 1 GTi. I do have a couple of friends who have never owned anything else. If it is a really solid car, and in as good as original condition, you could get a gem. However, these cars attract rust like no others, the front sidepanels (underneath the plastic arches), the lower front (behind the GTi lip), the subframe, and the sills are something you should inspect on rust or with crappy replaced non OEM parts. The engine is very reliable, and can take allot of miles, but still, this car is 26 years old, it will already have alot of miles, and since the standard dials only show 99999 figures, you will problably never figure out how much it really has on it. This also is the reason you shouldnt buy it as a daily, but just as a project. But as Quigs says, if you are good with tools, and have the space and time to do everything yourself, then you could use it as a daily. The car isnt advanced in anyway, so if you want to learn how to restore and maintain a car, this is perfect too.
Moneywise: Hard and well taken care of (original state) MK1 GTi's go for roughly 4000/5000euro's (6500/7700 usd) here in holland, which is about the same or even more then the price of a mint condition '94 MK3 GTi 16V.
You are correct about your first remark, i dont share your opinion on the 94car will be superior part. What is your definition of superior? An 81 MK1 GTi will outhandle, outaccelerate, get better millieage, give more driving satisfaction and get more thumbs up from VW enthusiasts, or even midleaged men who dreamed of owning one when they got their license in the early 80's. It is an Icon, which can't be said of the MK3 Gti, which is sluggish, underpowered and blends in with all the other traffic. This is a big trade up if you are a VW fan, or for that matter a classic car fan.