I've been in Disney parks probably 25 times before we knew about the buttons/before we moved to FL, and maybe 20 more times (with only an occasional birthday trip) up until 2years ago.
When my husband & I got married & moved to Jacksonville, we decided to buy the AP as a year-long Disneymoon gift to each other

since then, I've been decorating our buttons extra special since the cast get such a kick out of them

Since then we've renewed our APs and have been something like 30days over 12-15 visits.
Undecorated Birthday:
We have gotten a free hot chocolate (MK) on my birthday at like 1am in January, and my friend got a free funnelcake (Epcot) but they didn't say it was for his birthday, just said "no charge" when he went to pay. At DCA back in 2007 I got a whole bag of fresh corn tortillas at the sample stop
Decorated Ever After:
-We got a little lemon cake-puff dessert with chocolate drizzle at Via Napoli on our honeymoon trip, it just showed up with our check

-I mis-read our RnRC FP- tickets and showed up at 1:15 instead of 11:15

the guy said we were too late for our window and we walked away, I felt bad cause its one of Dh's favorite rides. 1min later another CM came up & tapped us on the shoulder and have us THREE anytime FP for it. We gave two of them away to other just married couples who had buttons later in the day.
Decorated/undecorated Celebrating:
-We've gotten tons of random magic over the years, the biggest was being asked to be in the MJJP at AK when we went with friends this winter.
-One time we were lined up 8:55am to meet Mary Poppins and a cast lady came out to tell us she wasn't going to be there today. I said "I guess will just have to squeeze in a stop at Epcot to get her autograph on the way out". She asked was i an autograph collector & i said i was trying to get 'non princess' characters to send to my niece for xmas. Then she asked for my name & autograph book and said "I can probably go find Mary this morning, you two go have fun, ride the rides and come back to GR after noon and tell them your name". We came back to 11 new autographs in our book! Very sweet of her

-one time we stopped mid-afternoon at a character greet to ask "will the line be shorter later tonight?" And the girl asked what are you celebrating. We said (kind of embarrassed) "not being at work?" And she let us skip the line - we actually felt guilty, cause we'd have been just as happy to meet the character at night.
-once at rope drop for TSMM we got stopped and asked about our buttons, and a few other cast came over to look and and questions too. After about 5-7min of fun chat with happy CMs they felt guilty that the line had gotten long with people going past us even tho we were there first. One girl gave us a rider swap card and let us go in the FP entrance.
-this trip we were celebrating a first visit to Flower & Garden Festival and a CM in a store stopped and asked for a picture with us, she said 'I wanna submit you for our cast newsletter' so we'll see if anything comes of that.
Mostly tho, we just get recognized by cast from former trips now and typically don't get perks, just friendly "you're back! I remember you! What are you celebrating today?"
EDIT:
I also made First Visit buttons for my niece and nephew a month back and while I walked away to set up their FP+ they went to do a ride without me. when they got to the line, a CM recognized their buttons from seeing me a trip or two before and gave them a coupon for a free Mickey ice cream. those kids (2.5yr & 15mo) aren't allowed sugar treats at home... So it was pretty much the best day of their lives