I spike my hair and it always gets harder to do as it gets longer. It's hard to find good gel that won't flake off later in the day, and the best brand I have found is Vital Care mega mega hold Extreme Spiking Gel (10+). There is a stronger version, but I haven't tried it. I've been using this brand for years and wouldn't use anything else because this has been the strongest I have used that doesn't flake, most gels will flake and you really don't want that!
But like I said, even this stuff is hard to use on hair longer than an inch. That might sound really short, but it looks much longer, (this is the first time I've actually measured it lol).
I have heard for really long hair people use egg, but that might attract some bugs so if you have really long hair I'd go to a good salon and ask them for tips and have them do it for you so you know whatever brand gel they recommend is actually going to work.
WHY? LONG HAIR IS HOT!
Buy some good gel from your local convenience store and if that doesn't work as your stylist to cut some shorter layers into your hair which will add more body to your hair and it will therefore spike up more effectively and last longer