Since CO is your only option for a lot of non-stops from EWR and you are ok with moving to an airline that requires a connection, have you considered AA? I'm an AA EXP (100k BIS, 100k Points, or 100 segs per year) and find EXP to be the best top tier around. The factors that compel me to focus more and more of my flying on AA include:

• Unlimited Domestic Upgrades - I've flown 156 segments this year with 94 of them on aircraft with F cabins. 93 have cleared. I book most of my flights last minute and still have that success rate.
• An Admiral's club at your home airport
• 8 System Wide Upgrades (eVIP) for International Upgrades- The big benefit of these instruments is that they work on virtually any fare, even deep discount Y. Since the current incarnation of eVIPs was introduced, I've only had 1 not clear.
• Awesome Redemption Availability - I've got tons of miles on UA, US, DL, and to a lesser extent CO. Nothing has compared to my ability to redeem on AA. EXPs also sometimes get "special" availability which further enhances my ability to redeem for what I want.
• Better Domestic F Product - The AA 737-800 F cabin is awesome and AA serves ok-ish food on almost all midcon flights. AA's minimum miles required for food are much shorter than other domestic carriers. Also, AA serves "snacks" (essentially lunch) on flights between AA's already more liberal meal windows.
• 3 Class International Service - While AA's international network is weaker than its competitors, the fact that AA offers 3 class service makes upgrades and redemptions that much easier. While AAs international F product isn't something I'd pick over BA, SQ, etc if I had to pay 100% cash for it, it is certainly better than most J products from US airlines.

A big wildcard from EXPs right now is what other changes are coming as the integration between IB, AA and BA continues. If they move towards universal upgrade instruments between all 3 carriers, the value of EXP will be further enhanced.

I don't really have a "home" airport and my flying patterns change every 20-30 days as projects come and go. As a result, sometimes AAs network works for me and sometimes it doesn't. It certainly has its strong points and weak points. Consequently I always have elite status on 2 or 3 other carriers. Generally, though, if flying from AAA to BBB on AA is no more than 1 or 2 hours longer than another airline I have elite status on, I'll take the AA option. AA treats its EXPs that much better and they handle us so well in IRROPs and other unexpected situations, that I feel like I stay ahead overall by flying a few longer AA flights and actually getting there despite weather, cancellations and other factors.

YMMV