I opted for the San Disk Ultra 512 SD card from costco. I just got a new dig camera and had been pricing the cards and costco just lowered the price by $20, so I figured why not? Plus I wanted to take action pics.
I think the costs at costco are comparable or less that at other stores after their MIR (mail in rebates) and that appealed to me.
Some brands of digital cameras will have a special feature that will only work if you use their brand memory card. I had an olympus like that but I can't remember what it did as I never used that feature even though I rec'd an olympus mem card as a MIR when I bought the camera.
As far as going thru security and your memory card, I didn't give it a second thought and mine were all fine going thru the security at the port. My camera and all mem cards were in my carry on that I placed on the belt.
One thing you might want to consider is buying a back up memory card so that you would have at least 2 just in case something does happen to 1 of them. I have never had a card fail but I've read about that. Also if you had a 2nd card you could take more pics if your other card was full. Mem cards hold different mb's so your 2nd card doesn't have to be the same but could be larger or smaller depending on your needs.
Also be sure to have an extra battery(s) so that you can use your camera for pictures while the other is charging.