That's plenty big enough for quite a few guppies
You may find they have some disagreements, but if you have enough any aggression is diluted.
I used to have guppies, albeit it with females, but never had any fights between the males
Unless you have somewhere to offload the hundreds of fry you'd get with a breeding colony, then I wouldn't advise getting any females.
Most Lfs won't take them
Thanks for the replies. I would have a few females but the 4 stores we have here will not take any fish from people anymore. So to avoid unwanted fish I would just keep the males instead.
Several males will be just fine together. The reason we advise people keep multiple females to each male is to distribute breeding pressures. With no females there is no breeding pressure. I just returned from the ALA convention where I saw simple fish bags with 10 beautiful males each being offered for sale at auction. Even in that tiny bag space there was no aggression, although there was hardly enough water to hold them for long. Mine went right into my water change bucket when I got back to my room.