I only want to sync one of my Marketo workspaces with Salesforce...is this possible?

It is not possible with just a setting. Marketo-SFDC make a 1-1 sync of the databases and in Marketo you decide which leads are routed to the Lead Partition/WS you want. For example, you could push Leads in North America to the NA Partition/WS, etc..

For your situation, you could instead create a field in SFDC that says "Ok to Sync" and then the Marketo User only can see Ok to Sync=T leads. If Marketo then syncs only those leads, you can tell Marketo to route such leads to a specific Partition/WS.

if Ok to Sync=T, then Change Partition=1

Hey John. It's not easy. Support does have to set this up, but we purchased Marketo on June 19 and it's still not fully synced. It's a big mess, and we've talked to multiple people within Marketo with no full solution. I've spent over 10+ hours on getting it to work with Marketo, and it's still not done.

Enjoy getting this done. Maybe it will go more smoothly with you.

John Could you give a few more details on why you want only one Marketo workspace to sync with SFDC? There might be a solution there that does not even involve workspaces.