I can certainly come at it from the first-generation perspective. I have a two-door '95 16-valve and we travel all over in it, often times pulling out little Dinoot trailer with a rooftop tent. This summer we did about 3,000 miles in it covering Oregon, Idaho, Utah, Colorado, and Nevada.
My Sidekick is lifted 2-inches and wears 235/75/15 tires, which are larger than stock. It also weighs about 3,000 lbs. thanks to my winch, bumper, rack, etc., etc. It's likely quite a bit more with my ARB fridge, gear, and boy my wife and me inside. My vehicle has 166,000 miles on it.
The trucklet is not fast at all. It will, however, cruise at 70 mph happily. It is not a fan of going much faster, although it will. We took it up to 80 once on the trip just to see if it'd do it, and it did, but screams pretty loudly. We quickly brought it back to its happy zone afterward.
One of the best things about the early generations are their simplicity. If you opt for the 8-valve engines, they're even simpler. Parts are super cheap and widely available world-wide, as these were sold as Vitaras all over the globe from 1989 on. The car has been dead-nuts reliable since I bought it four years ago. I have put a lot of work into it, and recently had the transmission rebuilt, too.
I have never driven a 99-04 Vitara/Grand Vitara, so I can't speak to them. But, I can say that my '95 has been great. If you do decide to go that route, I'd look for a hardtop of four-door version, or a two-door with a hard top installed vs. using the soft top, simply for security purposes.
My wife and I have dreamed of taking our Sidekick out of North America, and maybe we will at some point. So far, ours has been relegated to the U.S. and Canada.
- Andy