I dress in a suit with very rare exceptions. In all my years of doing events, I've lost just 1 event because of that. The client said, 'I felt like I'd have to 'dress up' to meet with you!' But considering they hired a $400 musician (one man band) over us at $1500 (currently, we're reviewing a rate increase for later this year) - and I'm ok with that.
Any networking meeting - I'm in a suit.
Events - I'm in a tuxedo because most of my events are 'formal'. And 'formal' doesn't have to mean 'stuffy'.

There are exceptions where I wear a suit, or khaki's/Hawaiian shirt, or even a raw silk shirt/pants - depending on the specifics for the event in question.
INITIAL client consultations - I'm in a suit, almost without exception.
Future consultations - Varies. Sometimes a suit. Other times I might wear slacks, shirt, and sport jacket or a suit coat. Other times a polo and sport coat with jeans. It depends on the client, the event, the meeting place, etc.
But there are a few things I've learned over the years.
1. Dress for success. You only get one chance to make a first impression. I want that impression to me that I'm a serious businessman - my handshake, smile, and the meeting will let them know I'm friendly, personable, and able to have fun - despite my being in a suit. This only comes about from being comfortable wearing a suit.
2. Dress for where you WANT to be - not where you are. That means, dress like the people you look up to in the business you're in. Marcello is extremely talented and successful. So is Mike Walters. I can go on and on with those people who are extremely successful in this business. They all wear suits. I wear suits.
3. Get your clothes tailored. While Marcello has his shirts tailored, I've not gone that far - at least not yet. But getting your suit tailored is VERY important for the fit and comfort. A 'big guy' in a tailored suit looks good. A 'big guy' in a suit off the rack looks fat. I actually had someone approach me at Mobile Beat 2009 and tell me he liked my suit (it's a 'white' ice cream suit) and how they wished they could wear something like that - but they couldn't because they were a 'big guy'. I told them it didn't matter. I was actually BIGGER than they were - but tailoring meant that the clothes FIT.
4. Have more than one suit. I have a half dozen suits or more along with a couple sport coats, at least 2 or 3 dozen ties, and pocket squares in at least a half dozen colors. Being flexible so you have more than one look is important.
5. Be flexible. If I'm in a suit, I can remove the pocket square and tie and be a little more 'casual'. I can drop the coat if need be, and roll up my sleeves. It's a LOT easier to bring a look 'down' than it is to 'dress up' a casual look. If I meet with a client and it's obvious the meeting is going to be more 'casual' I'll leave the tie in the car, and remove my coat - putting it on the back of the chair or potentially leave it in the car.
But if you choose to NOT wear a suit for some reason, that's ok too. I do what I do because it works for me and my business. What I do know is that there aren't ANY other DJ's that I've met that meet their clients in a suit. Most don't wear a suit to networking meetings. It makes me stand out amongst the other vendors and to my clients.