I love iceberg lettuce. My dad always bought romaine when I was a kid. Its okay, but it's no iceberg. Different strokes for different folks!
I agree about the problem of filling yourself up on just lettuce, though. Speaking literally, you can't do it. Lettuce doesn't have enough calories. What you can do is look beyond lettuce. Avocados are a very rich food and will go a long way toward filling you up. If you have onions, you can caramelize them and make French onion soup--the "meatiest" meat-free food I've ever eaten. With a smattering of all the usual veggies--such as carrots, celery, onions, tomatoes, cilantro, etc.--you can make soup or gazpacho. Add barley, split peas, or beans for a very filling experience. You could take a butter squash and turn it into a rich soup with a little cream and some spices. You could stuff a bell pepper with sauteed mushrooms, onions, and radishes. Broccoli and asparagus can be very filling, especially with pasta or rice. Add cheese to the list, and your options are endless. Ditto with potatoes and portabello mushrooms. Experiment with less common veggies, like jicama; those go very well in salads. And then, of course, there is tofu.
Open your mind, and you can fill yourself up with veggies. It just takes some creativity, some time, and some money.
But, honestly? Meat and fish are awesome. Add those to your diet, and life is ten times better.
