Thank you all for your replies. I think the compass isn't necessary for her first unit. You're right, I don't miss it in mine, although we have noticed that it's handy in the MeriPlat when searching for geocaches among boulder rocks, for example, when I can't move around much to get a direction signal on the 500. But lacking a compass may just add a few extra minutes to the chase, which is just fine.
As for the Magellan vs. Garmin, I am leaning towards the Magellan for all the reasons people have suggested, however, since she and I are in different states anyway, all help will have to be over the phone. I like what I'm reading about Garmins and I think she'll figure them out with no problem. Still, I'd lean toward the 210 except that I now have a new scenario. My brother has expressed interest in a gps as well (both of them visited and loved the geocaching). In his case however, he absolutely needs the autorouting. He wants to geocache, too, but he has no sense of direction when driving. He can't afford the large car ones, which would be great, but he can pull over and use the handhelds when he needs it. He's willing to spend $300. Now, if autorouting in a handheld is the primary concern, are the Garmins better than Magellans? If so, perhaps I should recommend a Garmin for him and get a Garmin for my sister and then they can share software for now (Garmin supports 2 gpsr, right?) and learn together (they are in the same city).
One thing that bothers me about Magellan's Mapsend is that in the turn-by-turn directions, long street names or exits are cut off and there's no way to scroll over to see the whole name. Not usually a big deal for me, but for my brother, it may be. Is this a problem with the Garmin software?
Another thing that bothers me is that there's no option to select alternoute routes on the fly (e.g. avoid highways) with MapSend. I've read on the forums that it's possible in the Garmins. Handy feature.
Thanks again!