Frontline has always worked for me, even when I lived in tick central (mid-Atlantic region) and hiked and worked sheep regularly in tall grass with my dogs. Just be sure you stick to the schedule because if you are a couple of weeks late there will be ticks. Actually, even with Frontline the dogs will pick up ticks, but the ticks will die instead of filling. Occasionally you may find a groggy tick wandering through their coats, but she will be on her last legs.
I will advise not to economize on spot-on treatments and to stick with either Frontline or Advantage. Some pet stores and feed supplies sell products that LOOK like Frontline and are dropped onto the neck, but they contain permethrins, which are the same sorts of chemicals you would find in a can of Raid.
Some people say that their local ticks have become resistant to Frontline, and advocate the Preventic collar, which is very effective. However, the Preventic collar contains an MAOI, so if your dog is on any other MAOIs (like Anipryl), SSRIs (like fluoxetine, AKA Proxac) or TCAs (like amitryptyline, AKA Elavil) then you should not use Preventic collars due to medication interactions.
I'm originally from Tickville Central in Maryland. It was so bad one summer we had to use both Frontline Plus and the Preventic Collar (on the advice of our vet). We ended up putting in the MaxForce Tick System that year and by the next year just had to use the Frontliine. I also sprayed the perimeter (adjoining the woods) of my yard with Permethrin every three weeks.