Integrated Products and follow up triggers

Hello all:

I am new to the Marketo CRM environment.

I would really enjoy getting some opinions and feedback on the following:

• What are the best add on products (SAAS) that you feel get the biggest 'bang for the buck'?  I am currently researching Sprinklr to use as my social network management platform and Informatica for SMS and real time polling and events. Both have pre-existing APIs with Marketo which make them very attractive.  Any general advice or thoughts is welcome.
• For an existing customer base, I was curious if anyone could offer any advice (or if you have read syndicated research, whitepapers etc) on how best to architect a smooth, flowing program to interact via Marketo (eg: triggers based on behavior or engagements- they look at my web page or click on a link in my newsletter) as well as triggers for personal recognition for various milestones (eg: career anniversary, birthday et al).  I realize this is a broad and vague question so any input is certainly welcome!

Thanks so much

MK