All this time I've been booking direct flights online.
But this time I'm thinking I should stop over in some city and do some sightseeing.
I'm planning on flying from SFO to DEL.
I would like to stop over in some city (like Munich or Tokyo or wherever) and stay a day or two.
But most online places don't let you do that.

What's a way to schedule a layover without paying lots extra for the privilege? And can I do it online?

Thanks in advance for your suggestions.