well, so many special dates coming up. Others have suggested experiences, which are always wonderful. Time together, making memories, good ideas.
A second thought would be a series of jewelry pendants---- each for the special date and sharing a theme, like this: for the anniversary, a bell shape with the 15 years' anniversary date engraved; for the 15 years in Canada, a national symbol (leaf?) with dates engraved; for the 40th birthday, a heart or star shape or the like, with the dates engraved. She could wear one, or all three, on a nice pendant chain. Instead of dates, you could also engrave "love" or something else special for you two.
Consider doing the flamingos and billboard on the front lawn she may be shocked at first but than she will laugh most people do. My wife did this for me it was hilarious especially when the dogs went and were sniffing out the stuff on the lawn got a few pics of this. Many companies do this sort of thing or you could also do the skit from SNL with the hole Dickinabox.
A trip...go somewhere for the weekend or take a longer vacation out of the country. I'm a HUGE fan of cruising and you can sometimes get some really great deals.
Take her somewhere she's always wanted to go or some place that holds meaning for the two of you.
How about a weekend couple's retreat and get an uncle to watch the kids or another family.
My wife's birthday is in a few weeks. I'm getting her a gun. She has a 38 for personal protection but she wants a 22 for target practice. We don't usually buy each other gifts but I was going to buy this for her anyways.
my birthday surprise for my wife is i love more than i said..this is precious moment of my life ..thank god i had been with you ,,,
if she likes surprises, make it romantic. hotel suite, rose pedals, champagne etc....or a getway vacation.
weekend at a B&B. A cruise.
Go on a cruise.
Get some Viagra and that will surprise her in the morning