I have the GW-7900MS-3 and love it, feels good on the wrist and easy to read. No need to add lat and long to the system for accurate tide info - initially you set high tide from info on the net or your local paper. Manual is here:
http://ftp.casio.co.jp/pub/world_manual/wat/en/qw3193.pdf
and this is manual for GW-9110, almost identical
http://ftp.casio.co.jp/pub/world_manual/wat/en/qw3217.pdf
Photos of mine:
Showing tide going out, close to low water springs, tide data set to close to my home at Chichester Harbour entrance. Background of photo is Hayling Island bridge and exposed mudflats - top end of Chichester Harbour
Not familiar with the 9110 which, AFAIK, uses the same module but doesn't use a fifth button for activating the light. The big selling point of the 9110 is the rust resistant titanium case though I haven't yet had a problem on the 7900 with rust, either on the stainless or the resin parts of the case
If price/performance is important to you then the 7900 is the one to go for. Aesthetics are important and subjective, for me the 7900 - in the guise shown above - is the better looking.
Bet that was no help at all!
