I was a vegetarian for nearly a decade. A vegan for a couple years. The memory is not fresh for brand names of tasty stuff but the rest should be good.
I had better energy levels, less excess weight, and believe it or not better sleep if I have the right mix of vegetarian diet. I think that the right mix of diet is somewhat individual, somewhat universal so you results may vary. In my case, its just eat as much vegetable protein as possible. Keep in mind you do need multiple types of vegetable protein to catch up on amino acids or take GNC suppliments that aren't vegetarian.
Cons are travel sucks to some parts of the country (South, Midwest, Upper Midwest) and countries (Korea, Brazil, Argentina, Germany, Jamaica), Lonely planet travel guides are veggie friendly and help.
Another con is there insecure asshats out there who will treat you as an ambassador for freaks and will never stop talking about how much they like eating meat, killing animals, torturing bunnies, and complaining about every conceivable variation of rabbit food once they find out your vegetarian or vegan.
Be prepared to say no thank you often as people try to force meat on you. Restaurants will take getting used to before you know what is vegetarian. Be sure to ask: is there Crisco, fish, meat, or pork in it? Is there any animals in the soup stock? Uses butter? As dumb as it sounds certain parts of the county seem to think fish or pork is not animal meat.
Trader Joe's, the world food isle at Giant and Shoppers food mart, and for the occasional strategic item Fresh Fields is your fiend. Any indinian grocery is great, try all variations of appa.
Go to Vienna, VA. Two places you must experience is Amma's Vegetarian Kitchen and Sunflower. Explore the menu than figure out how to cook it. You'll be happier. There is a restaurant out by the White Flint mall which was the three best affordable veggie places when I was looking for such things.
Don't overdo soy. High levels do weird things with estrogen levels. That said the jalapeno baked soy nuts at TJ's are the bomb.
Take vitamin B-12 supplements.
PM me if you want cookbook suggestions. I won't be home for awhile and cannot recall the titles and authors offhand.
PROTEIN IN LEGUMES: Garbanzo beans, Kidney beans, Lentils, Lima beans, Navy beans, Soybeans, Split peas
PROTEIN IN GRAINS: Barley, Brown rice, Buckwheat, Millet, Oatmeal, Rye, Wheat germ, Wheat, hard red, Wild rice
VEGETABLE PROTEIN: Artichokes, Beets, Broccoli, Brussels sprouts, Cabbage, Cauliflower, Cucumbers, Eggplant, Green peas, Green pepper, Kale, Lettuce, Mushrooms, Mustard green, Onions, Potatoes, Spinach, Tomatoes, Turnip greens, Watercress, Yams, Zucchini
PROTEIN IN FRUITS: Apple, Banana, Cantaloupe, Grape, Grapefruit, Honeydew melon, Orange, Papaya, Peach, Pear, Pineapple, Strawberry, Tangerine, Watermelon
PROTEIN IN NUTS AND SEEDS: Almonds, Cashews, Filberts, Hemp Seeds, Peanuts, Pumpkin seeds, Sesame seeds, Sunflower seeds, Walnuts (black), Hemp seeds
Also here's a decent summary from the Mayo clinic.
http://www.mayoclinic.com/health/vegetarian-diet/HQ01596