"Recommendation of" vs. "recommendation for" – what is the difference?

Solution 1:

Based on your clarifications, I think you can use 'recommend' in this way, but to make it sound more natural in SAE I'd reword your sentences to one of the following:

• We are happy to provide recommendations of X.
• We are happy to recommend X.

To my ear the second option using the verb form is more natural, and it doesn't require any preposition (of/for) before the object. But if you insist on the acceptable provide + noun structure, then of is the preposition you want (meaning a good report of something).

In general, though, to "provide a recommendation" has a meaning that's more commending than suggestive, and I think that's why this structure is less preferable to just using 'recommend' as a verb if you're more just wanting to provide a suggestion.

A few other notes, though. I switched glad to happy as that seems more natural in this setting, and your usage of good work you did is also a little awkward. Better would be good work.

In response to your second question to Zack above, I'd suggest "Please use this forum to recommend well done work."

Solution 2:

I would also rephrase the sentence as suggested by comments on the question, but about the difference in general (note: suggested "more natural" phrasings are for Standard American English):

• If I provide you with a recommendation of X, X is a thing you can acquire, and I am endorsing your acquisition of it (generally in contrast to similar alternatives). Example: you need a cleaning service, I provide you with a recommendation of a particular such service (perhaps the one I myself use and find to be satisfactory).

  This is more naturally stated as "I recommend X [to you]".

• If I provide you with a recommendation for X, the usual meaning is: X is something you want to do and I am recommending you to the people in charge of deciding whether you get to do it. Example: you are applying to a graduate program, so you ask me (in the hypothetical, I am one of your professors) to write a letter of recommendation (of you) for your admission to that program.

  This one can also mean that X is something you have already done and, again, I am recommending you to some third party because of it. Example: you are leaving the company where we both work, you ask me to write you a recommendation (of you, to future employers) for your work there. This meaning is more naturally expressed using a different word: I provide you with a reference for X.

Also note that "provide recommendation" is, in itself, incorrect in Standard American English: you need an indefinite article, "provide a recommendation". I am not especially familiar with other Englishes, but I have the impression that omitting the article in this construction is correct in some subcontinental-Indian registers.