The adjustable bench

I would recommend the adjustable types over the flat bench. The flat bench is limited in use.

Here are the many exercises you can do with an this bench.

Flat bench press

Incline bench press

Decline bench press

Situps

Incline dumbbell curls

Seated shoulder press

Incline dumbbell flies

I use the Hoist HF-4165 6 Position Bench.

It is a well made piece of equipment and I highly recommend it.

It even has optional accessories such as leg extention and preacher curl attachment.