My go to watches (as in my only watches) are:
Casio Oceanus OCW600
Jikan Watch Blog: Review of Casio Oceanus OCW-600
I have the leather band. I have been searching for a titanium band, but don't want to buy a whole new watch to get one (and their support laughed at me when I called to try and buy one; they said they stopped making that watch a long time ago
) I love this watch.
Invicta Pro Diver Carbon Fiber Blue Ltd edition (or some such name)
Lt. Edition Blue Carbon Fiber Pro Diver | Watch Talk Forums ARCHIVE
This is the watch I wear to the beach and when I am swimming in the rivers and springs here in North FL. Got it for super cheap off eBay (and even new they are still pretty cheap, they have a ridiculous MSRP and sell for like 80%+ off)
My most recent watch is the Padron Tessera, which I got from a Kickstarter campaign:
https://www.kickstarter.com/projects/padronwatchco/tessera-a-150-meter-25-jewel-mechanical-timepiece?ref=nav_search
Welcome to Padron Watch Company - New, Vintage, and Classic Watches of Distinction
I actually got two of them; I have a stainless with verdigris dial, and I also have a black one with black face. The stainless is the one I have been wearing since I got it, and the black one is new in box, I am going to try and sell it but there is another one on ebay right now so I am waiting for it to sell first. He keeps dropping the price, I may just hold on to it for a few years and if the Padron watch company name takes off, and once the first run of them sell off, then maybe I will sell it. I don't think it is any lighter than your citizen.
If you are looking for light and don't mind quartz (sounds like you don't) you should check out Skagen watches, very thin and light. A friend has one and it is pretty sweet.
http://www.amazon.com/s/ref=sr_in_s_p_89_104?rh=n%3A377110011%2Cn%3A%21378 516011%2Cn%3A6358539011%2Cp_89%3ASkagen&bbn=6358539011&ie=UTF8&qid=1404828632&rnid=2528832011
Steve