Guinea pigs do need a companion. You're right, Cali, that not all guinea pigs get along - that does not mean that they will be happy alone. Two of my guinea pigs do not get along well at all, so I've separated the six of them into two hutches. They are very close groups. Some of them even have 'best friends' - Opal and Kennedi have been together since the moment they were born (they are sisters) and are never apart, even when out for a run. No matter how many pets a guinea pig gets I do not think it is comparable to the companionship of another guinea pig.
And TM, if you do get a male, please get a neutered one. If you got one from the SPCA wouldn't it already be done? If it was neutered you could even have a male and female - Maverick was neutered, and he got along fine with all of our females.