Last year I have been submitting my CV to different faculties for a lecturing position. Of all the ones that I applied only one was more serious and wanted to keep in touch (institution A), the other one (institution B) was completely silence and only they reply with a general "we are interested, but we will tell you when there are open positions". Actually the following has happened:
Institution A has offered me a full time position with good salary, and the freedom to make research or even to work in other places part time.
Institution B contact me a few days before the offer of institution A, telling me that they would like me to work part time with them; when I told them that I would like to have a full time position they started to tell me "that procedure is going to take time". A couple of days passed and I got the offer from the job that I mentioned in the first point.
Now last week Institution B called me and they told me that they want not only to offer me a full time position, but also a position as a student coordinator of the career. The drawbacks are: the salary is 14% less than A, the hours are not; fixed that means that one should stay for overtime unpaid if the goals have not been reached, the research is keep to the minimum and I will not have the chance to work in another place part time. The only benefit is that I will be have a higher rank than in A. This same institution has already booked me for some partial hour lecturers in a couple of courses. I have been sincere with them when they called me and I told them that I have been offered another position (from institution A), so I need to wait to their answer. Even with that institution B has continue insisting me for getting the job with them.
So by factors of time, research and money; institution A seems a pretty good choice, but how I can reject politely the offer from B without being "marked" for not working there or not to burn bridges with them. Maybe somebody could say "why I do not want to burn bridges with them?, well it is just to have like a backup plan. Also institution B has the story that they are used to cut off their lecturers at any time they want, so what to do?