I've had an Eris for about three weeks, also on Verizon and use Macs, I like it a lot, but does not connect well with Macs. I can easily connect via USB and transfer files, but have had no success with Bluetooth.
Sync iCal and Address book via Google calendar & Gmail contacts. Took a while to figure this out but it's working now. Haven't bothered with any third party software - figured it made no sense to spend $$ for software for a free phone.