Efis and other leading technology

I am planning the upgrade of a Piper Navajo panel. I wouldn't mind
spending the money for "cutting edge", but it is not clear what is
avialable and the infrastructure to support it. Could anyone provide
informed councel on EFIS or other certified options?
My questions are along the following:
1. Should I install Skywatch/Mode S or wait for ADS-B (I fly east
coast)?
2. Ditto on satellite weather?
3. Are any of the "economy" glass panels certified for retrofit?
I curently have a Garmin 530 and steam gauges.

Thanks,
Mark