You don't join a startup/small business because of the best traditional benefits like a 401k, you join because of the challenge and chance to make a huge impact

You don't join a startup/small business because of the best traditional benefits like a 401k, you join because of the challenge and chance to make a huge impact. You need to figure out what type of environment you are best suited for, a startup or a larger enterprise. They are extremely different, so that is really the decision IMO. As far as switching after accepting one position, it generally burns a bridge, as would being there for 2 weeks then jumping ship. At the same time, employers have very little loyalty anymore, so if I felt it was right I'd change my mind, but with dignity and honesty to the parties involved. e.g. I wouldn't do it without being up front. Your reason can be as simple as you thought it over and felt that the small/startup business wouldn't be the right environment for you personally at this time and it wouldn't be fair to them either if you wound up only being there for a few months, so you have decided to continue your search... Or something along those lines.