The ICPI class will definitely be a good investment. The information and standards they profess are a great guideline. If anyone other than those in the industry knew what the ICPI was the certification would be much more meaningful.
I have been involved with all of the Rutgers classes and know you will get some good information from all of them, depending on what your actual skill and knowledge level is and what you want to know. The courses they offer for the certificate for are as a group, are an excellent source of primary information and should be concentrated on before venturing into the more glorified programs. As an example, the knowledge about soils and drainage are a precursor for installing pavers, SRW's, landscaping, and turf or plant maintenance.
The Paver class is a very baisc program that maybe redundant to the more intense and certified ICPI program.
The SRW class will cover the basics of wall and step building.
The Water Feature class will enlighten you to sustainable pond building and pondless features.
Intro to Plant ID is a course anyone that fancies themselves as a landscaper should take and have a much better understanding of how and what grows around us. The instructor in that program is amazing, and you will be given a great deal of information and work in two days. If you can afford it, the Basics of Plants for Landscape use is an intense and mind expanding experience. In the new 5 day format, the information will come fast and vast, but if you are up for the challenge and you really want to understand what plant goes where and why, this is that next step.
The Pruning and Advanced Pruning classes will teach you the proper ways to prune what, when, how and why. They will teach you that gas powered shears or not the first pruning tool you should be reaching for and why, and when they are appropriate. You spend plenty of time outside practicing your new knowledge.
The Principles of Landscape Design is taught by two excellent, knowledgeable and practical instructors. And yes, they are artistic and talented as well. This course will give you the basic theory with flair and style.
The Landscape Lighting class is taught by the owner of Cast lighting and will give you the basics of installing lighting using a hub system and some basic design, marketing and selling information.