With UA now revenue-based, and you purchasing the cheapest economy tickets possible, you really need to reconsider that relationship. On a typical $800 NYC-HNL fare, flying at the 50K level, UA will give you 6,400 miles (probably a little less as the tax portion won't accumulate miles). You're not going to be booking a lot of award travel when you're bringing in 6,400 miles per round trip ticket.

At AA, at the 50K level and a connection at DFW, you'll earn 100% flight miles plus 100% bonus miles, so a LGA-DFW-HNL would bring in over 20,000 miles round trip, over triple what UA would provide.

UA does provide complimentary domestic upgrades at all levels, but you would have UGS, 1K and Platinum flyers ahead of you and might not stand much of a chance. AA provides 2,000 miles worth of domestic upgrades for every 10,000 miles flown ny non-EXP elites and only provides complimentary upgrades at the EXP (100K) level. Neither carrier offers free international upgrades (you'd be looking a miles and cash).

I'm not up on Hawaiian's program. Don't know anyone that credits to it.