i bought mine over the phone from RFL today. i bought 9. the only way i could get 9 together (and i was happy to have them over two or three rows if that helped, so long as we were all close enough to communicate with each other) was if i got the very back rows of the west stand (our end) or the 3rd tier of the north stand. there are plenty of tickets in the 3rd tier of the north stand - eg, i was offered the 8th row near the half way line (£21 each), but if you want to avoid the 3rd tier of the north stand (which we did) you need to move fast.
if you are only buying 1,2 or 3 tickets you'll be able to get tickets lower down in the west stand. don't forget if you are too far to the right of the sticks (as we look at them) you will not be able to see the big screen. that annoyed me last year. though our end is not great for the screen anywhere really.