I have over 20 years experience in mapping and modeling in the petroleum industry using industry-specific software. I would really like to expand my fields of interest and my knowledge base. To this end I have begun working with a couple of non-profs in different fields and learning what interests me - and where my skill set really is - and getting some training in ESRI/Arcmap.
If I wanted to 'up' my credentials in order to procure more paying contract work from more varied clients, do you think it would be more beneficial to pursue a graduate education in GIS (either a graduate certificate or a master's degree) or would it be more useful to gain an ESRI certificate?
To employers, do either of these matter, or is it more the case that I just need to gain more varied experience through training and volunteering?