I think RTW is okay if we do it the right way. Here's my ideal RTW bill:
1. Paying Union Dues is optional to work at a given business, but it is required to receive union-negotiated pay, benefits, etc. (It's unfair for people who pay Union dues to receive the exact same package as people who don't bother to pay such dues. Those who don't pay dues must negotiate directly with the business for which they work. People shouldn't be forced to join unions as a condition of employment, and by the same token, Unions shouldn't be forced to provide any union-negotiated benefits to those not paying union dues.)
2. Yellow Dog Contracts, which prohibit workers from forming or joining unions, would not be allowed (this would help ensure that Unions available yet optional, which I believe should be the goal of RTW.)
3. A statement along the lines of "In no way shall this bill be construed to say that Unions are generally bad or should be prohibited. It just allows people to choose whether they want to be a part of them and the benefits they may include, nothing more and nothing less."
Or you could just do nothing. The whole necessity of laws like this is a false dilemma.