For (very) formal dining: Bromes Howard Inn.
The food is American/French, and always excellent. But the atmosphere is a bit stuffy.
For casual dining, my first choice is Stoney's Kingfisher on Solomons. They offer the very best crab cakes on the planet Earth. I recommend you avoid the BS and go straight to the bar and grab a table, where you will get the same great food and best service. Crab cake sandwich goes for about $17 these days, with a softball-sized crabcake presented in a half-stale bun with a dill pickle spear and a side of slaw.
The Pier on Solomons is trying to get together, and doing a fair job of it. For scenic view it reigns supreme. The food is good, and getting better. Since it is a Stoney's restaurant, I guess you couldn't do bad by ordering the crab cake. Expect extraordinarily long waits on the weekend, both to get seated and to get your food. (But like I said, they are just getting it together, having been open only a month or two.)
CD Cafe on Solomons caters to the artsy-fartsy crowd, and does offer up some good chow, but luck better be on your side. The portions are tiny, the prices high, and they depend upon their pasta menus to fill people up. CD doesn't accept reservations, so expect to wait in line to be dissatisfied. I only mention it in case you have a fussy wife who drinks tea with a pinky raised, otherwise it is best to ignore. (Their best dish is the savory cheesecake with a basalmic vinegar reduction... PM me and I will give you the recipe.)
The Tides is a very visually attractive restaurant and does offer some of the best food in Southern Maryland. Problem is... What is the best food that day? They offer everything from diamonds to coal and it is difficult to discern what will be good upon your order. Their lobster bisque is always good. Fresh-shucked oysters are always littered with shell, and at 2 bucks a pop makes me yearn for Acme or Felix' in New Orleans (at ten cents a pop). I have always wanted to try their foie gras prepared three ways, but due to the inadequacy of the waitstaff was never provided the opportunity. I had a rosemary cream steak that shocked me by how fantastic rosemary could be combined with beef. At the same time, my date was presented with a piece of fish that smelled not-so-fresh. The Tides is OK, but you have to accept it as it comes.
Dry Dock on Solomons is very good. Same thing with DeGiovannis. You will never get a bad meal at either of those places, but they both fail the "Dang that was delicious/Dang look at that bill" ratio. I can sling you a plate of 'linguine al pescatore' for a lot less than $20.
Lexington Park has a Vietnamese noodle joint called the 'Hot Noodle' which is different, but I find absolutely horrible. Absolutely flavorless, as opposed to the wonderful incendiary-hot dishes from the Mekong delta. I asked them to 'spice it up' and they gave me a jar of pepper relish.
So, hmmm... If I wuz you I would begin my SoMD culinary experience with Stoney's Kingfisher on Solomons.
I wrote on another thread about how the manager was a complete troll and completely abusive to some poor bartender. THe guy was screaming at her in front of all of us who were eating on the patio! 
