I guess it depends upon the types of vessels you want to use and their size, how big your table is, your budget, and how much you can live with range compressibility.
1/700th and 1/600th minis/models look more impressive on the tabletop, but cost more each. PT Dockyard also produces a very nice range of 1/700th scale modern patrol vessels.
There's also 1/1200th and 1/1250th, which are a nice compromise too – very wide availability, but some can be expensive.
1/2400th is quite small, but more affordable, and better for truer missile range ratios to your ground/water-scale.
I've got some surplus, 1/700th aircraft kits, if you decide you want/need aircraft for your games.
A lot of people use 1/600th and other scales of aircraft with their minis, and you can use larger ones with your smaller vessels, just rationalizing that they look larger since they are closer to you, with your gods-eye view of the tabletop.
If you want to do primarily close-in gun battles between patrol vessels, I'd go with the larger scale(s).
Feel free to e-mail me, if you're interested in the jets, or have any other questions. I have US Navy and Soviet/Russian aircraft plastic kits, unused, in new condition:
rkentjr AT Hotmail (d0t} c o m
I hope that helps.
Sincerely,
Rob