Laz,
I've had a 65g setup for almost 2 years now and if your going that route let me give some of my input.
Return Pump:
Stay away from the mags and QO's unless your going to run your pump internally. If your return pump is going to run internally than a mag 7 would be fine, just stay away from the QO's all together. If you’re going to run your pump externally than an OR2500 would be an excellent choice, Ehiems would be an even better choice but for the price, energy usage, lack of noise and cool running the OR2500 is just as good.
Lighting:
Again if you go with the 65g there's nothing that says you HAVE to go with a dual 250w setup as I think that's a bit of overkill in light and heat. If you take the dual 250's and the dual 96w VHO's on a 65g that's over 10w per gallon. Too much in my opinion. I went with a Current-USA 36" single 150w 10k w/184 watts of PC and it's works well but I'm going to upgrade to the new Current-USA dual 36" 150w w/T5's and I think that light will be more than sufficient. That light wasn't out when I initially setup this tank and I've never had heat issues. Also I went with an open top setup which I love, you just got to be careful what you stock your tank with and you might have a couple of carpet surfers. Knock on wood I haven’t lost a critter yet to any carpet surfing.
Skimmer:
I think you’ll be fine with the ER-180 but I use an EV-120 and have never had any problems with it. Just keep in mind where you’re going to run the skimmer. Again keeping with the 65g in mind there’s just not enough room under the stand of a 65g to fit a nice sized sump and skimmer. So what I ended up doing was installing a sump/fuge that took up most of my stands space and using a skimmer I can run externally (AquaC EV-120). I installed a shelf in the rear of the stand running the entire length of the stand about a foot up from the bottom and my skimmer sits on the shelf with water being plumbed up from the first chamber in the sump and it returns back to the sump.
Filtration:
Definitely go with a Fuge and scrap your idea of going with a wet dry. It’s a mistake many of us have made. Speak with The Saint regarding having a sump/fuge made
Circulation:
The 2 Seios would be fine, but newer methods of moving water have come around the last couple of years. It would greatly benefit you if plan out each part of your tank with circulation being just as important as any other. On a 65g two Koralia 4’s on each side of the tank would be fine. I initially went with a SQWD on a closed loop using a Mag 7. Well as I’ve mentioned not to use a Mag externally I had to re-think my closed loop idea as it just didn’t work the way I wanted not to mention the Mag running externally leaked. I then went with an Ocean Motions 2 way on a Gen-X PCX-40 1190gph with a bypass going through a 15w UV light. MUCH better design, and best of all very little maintenance needed.
Stand:
Go pick up Mels (Reddawg) stand for FREE!!! It’s nice as I’ve seen it and it’s a little taller than a standard 65g stand which will give you a little more room to play with.
Laz if you do decide to go with the 65g I invite you to come over and check out my system as if I would have had another like system to compare and take notes from I would of save A LOT of $$$$.
Later and good luck,
Lou