I would recommend the 120 over the 125. The 120's foot print is much easier to aquascape with its 2' depth. Also the increased height is a pain to work with and light. Go for the 120. You'll be happy you did!
I did a 60/40 base to live split (more base than live) and inside of 4 months you couldn't tell one from the other. I started with 100# of base in my tank. I added 60# of live to it (from www.liverocks.com
) at the end of the cycle and it has done very well.
There are frequenly local reefers (I'm in NJ too) who are selling live rock (NortheastAquatics.com has some right now at 4$/pound, just call them ignore the message on the home page they just need to revamp the website) and you can usually get that for 2$/pound. If you buy your base rock at Tropaquarium in ocean you can get it for 2$/pound to get you started (you have to buy over 100# to get that rate, but if you buy 100# it is cheaper than buying 70# at the 3$/# rate.
I put together my fishlist using LiveAquaria and WindowtotheSea as between the two they had very good information on who can be kept with who and what.
If you want corals skip the PCs and go for a MH
fixture or start with a retro kit that you can add the MH
to later rather than a unit. Trust me!
is a great source of information and contacts. Good luck starting up your tank!