4x4junkie
Explorer
Now if tight diehard Jeeps are your thing, still, the Explorer may not even be the best choice for that, given the TTB or IFS suspension setups even if you modify it. You'd be surprised where a stock Jeep can get you. If casual dirt road driving every once and awhile is your thing, Explorer might work with a RTT. Driving is 95% skill, 5% vehicle.
A 1st-gen Ford Explorer with the TTB suspension will take you anyplace any Jeep can go if it's built correctly, both stock-to-stock, and modded-to-modded. I know this because I do it all the time with my modded BII. As was said above, it's an exceptionally robust suspension with lots of aftermarket support. The TTB will handily leave any Jeep in the dust if you like to go fast in the desert.
I did not get the impression the OP is looking to go rock crawling however (or speed-running for that matter), so it's extremely unlikely he will ever run up against the limits of the Explorer's TTB suspension (even a later 2nd or 3rd-gen Explorer with A-arm IFS could very possibly meet the OP's needs here, which there is a somewhat decent amount of support available for also).
That said, I do agree with the general consensus here. You really should base your decision on whether things like it's size and interior room are what you want, and what compromises you're willing to take for it, such as regarding MPG (plus consider the fact you already have it). The Suburban no doubt will accommodate a heck of a lot more gear, and will also be more practical should any little ones start coming along. The Explorer however no doubt would fit better on really tight trails (which is only a very small percentage of trails anyway... I don't think there's any trail in Death Valley for example that a Suburban would have an issue on), and should get about 30-50% better MPG (about 18-24 vs. 12-17, depending on drivetrain configurations).
Also think about any future towing needs too (boat and/or a travel trailer)... The Explorer is good to maybe around 5000lbs, where the Sub should have no problem probably up to double that.
Indeed I drive a small BII mostly to get to those few intimate rewarding places a Suburban could never reach (think Ershim or Grouse Lake in the Sierra mtns). However trails of this type comprise probably less than 2% of the total places I go. I guess it really depends on how important to you getting to such places is. Certainly there have been times within that other 98% I could've used a bit more cargo room (at least there is some cargo room... I don't know how anyone manages to camp for more than a couple days out of a 2-door Wrangler lol).