Heated electric seats. Once you have them, you will never go back.

Leather (spills clean up with a wipe).

We also have the roof bars and use them with a cargo carrier. This
really helps on family trips since it can hold bulky items like
sleeping bags that take up a lot of rear cargo area room.

Less important:

In-dash CD player. We have a changer and never really use it.

The wood dash option really dresses up the 70 series interior (without
it the interior has too much plastic showing). This is a $500 option,
new. Not a must-have but I really like it on my 98 S70T5.

I could loose the sunroof and never miss it (but GLTs come with it).

I have TRACs but don't need it where I live. I think you get TRACS with
the heated seats (cold-weather package) so no way to avoid having TRACS.
The 99 models TRACs equivalent would work better then the 98, though.

If you plan to carry a dog, there is a pull-up net that
isolates the cargo area and keeps anything back there from
flying through the air. We just leave it up on ours.

I'd like the third row rear seat but my wife says no since that would
just tend to get her volunteered to haul around even more kids. So for
her, that is a deal killer :)