I have an Acer A100 7inch tablet, which just upgraded itself to Ice Cream Sandwich. This has external dimensions of about 7 1/2 by 4 1/2 which I find ideal.
Two problems are the battery life - about 4 hours, and the rubbish built in GPS. As a WiFi only model I believe I could get a more reliable fix with a 3 MiFi, but still not good enough, so I have not used it much in the air.
I have Memory Map loaded, with a couple of 1:250,000 maps which are useful even without a GPS.