Hi H.,
You've gotten some good answers so far. Ultimately, you'll figure out what works best in your situation, though.
My first child sucked his thumb - and still does sometimes, when he is tired (he's three). There was really no stopping it... he was sucking his thumb in his last ultrasound pic (lol.) But he understands that "Big boys don't suck thumbs, babies do" and has really cut back on sucking on it... except at bedtime, ofcourse.
My second child never sucked his thumb, and we wanted to stick with a pacifier for him. Well, it worked great and kept him quiet, and he pretty much only uses it when he is getting ready to take a nap, or on an outing when we'll be out for a while. He is weaning himself off the pacifier, and throws it across the room most of the time now(lol.) He just turned one last month.
Wonder how my third child (due in Feb) will be!?! You just never know.
Take care and God bless,
I.