In the past few months, I've actually run accross several Bicentennial quarters in my change. This is after a long period of very rarely ever seeing one in circulation. I just spent them again. Overall, they were in noticably better shape than the typical quarter from the 1970's - likely people have been cashing in their hoards.
I was rolling some change today and I found 2 (I rolled $40 worth of quarters). They'll be going to the bank eventually so they're out there if anyone needs them. Also, while discussing bicentennial coins, there was 1 Ike coin in the jar I went through - 1976. I was also given $77 worth of halves the other day by my aunt who thinks they'll be very valuable someday and I found 17 of them (and a 1969 40$ silver). She said if I get desperate I could take them to the bank. They're mostly early 1970s but none of them are that great and they're all circulated (or as circulated as a half will usually get) but I feel guilty about getting rid of them since she seemed so proud of them. She also gave me a couple Mercury dimes which she though were worth $20 or more (they were in average condition but they were all common dates). Most of that was pretty off topic, oh well.
I haven't gotten on in about a month or so, but overall through the past year, I have seen more than I can recall. I was saving them for my brother for a while (born in 76), but there were just too many. Granted most of them were found in bank rolls, but I probably had 30-40 of them before I even started searching rolls. I do know that many people save them, thinking that they must have extra value because they are "different"
I have got a few in the past few years, once 2 in one day. I like them so I keep them, its not about the value or lack there of to me.
I find a few every now and then. I have collected them only to "let them go" a while later. I did pick up an NGC 69, 3-coin , '76, silver proof set recently. The coins have these tiny dark spots which make me wonder about the grades. But I like them overall and will hang on to them as my tyoe set.
I see them quite often. But I buy rolls and go roll searching, so that ups the chances. I see them in change fairly often.