The NEA shuttle is a reliable if plodding service every 15-20 minutes. It drops off first at Newport Bay, then Santa Fe, Seqoiua Lodge, Cheyenne and New York. Paying as you board is fine, and they even take credit cards. The TGV service is less frequent overall, but there are a good number of trains at peak times and the journey is only 13 minutes - less than half of the bus. I think I posted a note of the TGC services a while ago, so I'll look for it! The RER line is the longest service of the lot, and not recommended with a lot of luggage!