Though you can do most of vegetables in polyhouses study market price in your area.

1. There is no sense of growing lettuce in polyhouse in winter as rates are very low all over India.If you want to grow round the year and have market for same then only think of polyhouse for growing lettuce.
2. Growing Cherry and salad tomatoes, cucumber and red yellow capscicum is advisable as production of such crops has far better yield in polyhouse.
3. Off season you can grow broccoli and lettuce march to july in polyhouses.
4. Growing zuchhini is always better in open unless you get parthenocarpic seeds suitable for polyhouse.
5. Asparagus, baby corn and sweet corn should be grown in open only.
6. Baby corn and sweetcorn are such crops that you may get more money by selling fodder than cobs ☺️