I did tons of research on the sat phone lineup.
I'd go with Iridium or Inmarsat's new line.
Globalstar originally had a better coverage map, it didn't cover the poles like Iridium, but it covered everywhere else. The problem was globalstar satellites orbit passed through the South Atlantic Anomaly which degraded the high speed data and voice communications abilities of their satellites. I guess they didn't design shielding for the radiation of the Van Allen belt, that's the official explanation at least. It can still send txt data fine, which is the system used for trucking fleets and for the SPOT messenger service.
Globalstar had to realign their unaffected satellites and that caused all sorts of changes in their coverage. You can get an program that computes your voice coverage it any given area, it's pretty bad, I checked for Burbank coverage and I can only make a voice call during 2 20 minute windows at any given day.
Iridium is better system, it's also the only satellite system that can pass/route calls from satellite to satellite, the other systems have to route through ground stations and then back up to space again.
The best plan I found was around $30-40 a month for a plain emergency plan. $1.29 per outgoing voice minute/text or email. Incoming communication is free.
If you plan to use the phone on a semi regular basis you can get prepaid minutes cards, some have minutes good for 1-2 years, but the good thing about them is if you buy another card, you can rollover your old minutes and keep them.
I don't plan to make more than 15-20 minutes of calls a year so I went with a monthly/per minute plan.
I think you'll see a change in plans soon. Iridium is about to launch a new generation of products, including a new handset: Iridium extreme and a Wifi mobile hub that will uplink to a iridium phone.
http://www.iridium.com/products/iridiumextremesatellitephone.aspx
Go figure this comes out right after I buy the 9555 handset

I'm not sure if the new handset is shipping yet. The system is backwards compatible, if you can find old used motorola and kyocera handsets, they'll still work.