my .02:
Don't waste your money on the earpiece mold thing. I have a Sennheiser and will be replacing it with the Bose and Iflymike when the Sennheiser dies.
I have Landerwood shirts (Model #700)
www.landerwoodshirts.com and actually do like them better than the ones from Pilot House
www.pilotshirts.com (Model TOFS). Although, I did have two of the Landerwood with the seams jacked up. My neighbor sewed them up for free...so I guess I got lucky.
As for as bags go, I have a PNS or Luggageworksonline Bag. In it's previous life it was an anvil. It still weighs as much...but someone added wheels, some Cordura® ballistic nylon and a handle. I think it's more functional as an anvil.

On a positive note, it is sturdy and you won't have to worry about anyone stealing it.
Another option in lieu of the Costco bag are ones from E-bags.
Note: the price shown on E-bags website doesn't include any discount. Place the order through SWALIFE and the price drops to $139.
Here are two models to choose from.
http://www.ebags.com/ebags/pilot_plus_22_upright/product_detail/index.cfm?modelid=63463 This bag is $139 after getting the SWA discount.
I sent an e-mail to the guy at e-bags who designed this new bag asking if it fits in a 300 or 500, and he replied saying he would have someone at LUV FLT OPs fit test it for him and get back with me next week. It looks like they did a lot of testing with this bag...designed for FDDOs or folks with a laptop.
About two weeks ago I saw a Capt with this bag which is $99 w/ the SWALIFE discount:
http://www.ebags.com/ebags/professional_22_upright/product_detail/index.cfm?modelid=8889
You will need an employee # and password, but can order these through SWALIFE after linking to the "LUV Culture" tab, then over to "discounts" on the left side of the page.
I'm not endorsing E-bags, as I don't have one, but if the new one fits, I give it a try for $139.
Congrats on getting the call...and enjoy your time in Dallas.
Yahtz