Lettuce is a favourite in our house. We love romaine (cos), endive (frisee), escarole, radicchio, red batavia, mizuna, lollo rosso, and little gem. We can have lettuces every day; little and often is better than lots all in one go.
As said before iceberg is one to avoid as it is very high in water; 90% water I once read.
Tomatoes are good with or without seeds. However, we really don't like tomatoes with the insides still in, so Laura scoops the seeds out and just gives us the skins. We can have a few cherry tomatoes a day, and it is very good and nutritious for us!
Pear is fine, but as with all fruits should only be given every few days. Most fruits are really high in sugar, acid and water - all of which have various health issues linked.