JMO, Tony getting a lawyer does not represent guilt to me, rather it represents intelligence.
He got mixed up in a pretty hairy situation here, and there have been a few spins leading to suspicion of him. I would get a lawyer too. Not only that, but I'd guess, he has spent alot of time thinking back to what Casey has said or done before all this, and some things are adding up, probably more so with him than with anyone else involved except maybe the GP's.
Also, I see alot of people feel that Tony should have questioned why Caylee wasn't around. I RESPECTFULLY disagree with that. The relationship was very new, and Tony is a young guy. Unfortunately, there are a lot of men in this world who just don't "see" children. They never feel protective of them, some don't ever want to have them. I think that most likely, when Caylee was not around, Tony either didn't question it at all, or he thought "This is great, I don't have to deal with the kid". I don't think that means he's heartless or involved in Caylee's disappearence. I'm just trying to be realistic about how a man his age might act/feel about a 2 year old kid in a NEW relationship. He was dating Casey, not Caylee. I doubt Caylee entered his thoughts a whole lot before this case became so public.
Just my opinion.