I am British, legally married to a Thai national with our own house and a 3 month old baby.

I work a 28 day 28 day off rotation outside Thailand.

I enter on a 30 tourist visa but always worry that one day that things could get difficult as I am in Thailand 6 months in a year.

I make a point of carrying company documents to show I am in full time employment and have been assured that I could get a Non-immigrant visa in my country of employment but do I need one as they are expensive and I only stay 28 days.

I may consider buying a small business in the future that my wife can run but I would help with when at home but would continue to work abroad also.

I don't want to step even close to outside the law and have to cover every angle as my wife and daughter are the most important things in my life.

Is a non-immigrant visa a good thing to have for the future or is it safe to continue entering as a tourist??

Although I am of the basic view that we are born and remain a tourist others don't take that view. The number of tourist visas will likely cause questions to be asked even if accepted. I would use your marriage to obtain a multi entry non immigrant O visa. This would be one expense every year and allow you more freedom (driver permit etc).

Be aware you can not work in Thailand without a work permit. So you might want to make sure any business it set up with that in mind.

What a good answer lopburi, you should be an admin cant we swop you for someone who would of just made the guy feel bad by calling him a worthless 30 day abuser, think you know who i mean!

Is that sarcasm between old friends/rivals or a valid comment??

That's really what I need to know if I am unwittingly a visa abuser I don't want to be!!

no sarcasm, the advice by lopburi is sound

It is a cheap shot at me. He doesn't worry me one iota. Your situation has you flying in and out of Bangkok regularly, so you are in a far better position than those who simply walk across borders and walk back in. However, it is strongly rumoured that by mid year back to back permits will be limited to 2 a year. Now it has to be said that although privy to info, nothing can be said to be absolutely certain just yet, although according to some posters, problems have already begun at walk border points. Again, you are a month in, and a month out, and thus not a back to backer. For the time being, I see you as pretty right, and you are married to a Thai. I think that a Non-Immigrant O visa has some prestige for you in a sense. It shows some committment to Thailand, enables you to get things like driver's licenses etc. But it is a personal preference thing at this stage. If you do want to work, it is possible to get a work permit on an O visa. Good luck.

Many thanks for help and comments!