Lots of on-site work, companies like Accenture or Deloitte will have jobs like this, but my impression is they don't treat developers very well (ie see them as very junior to the businessy folk). The shots are always called by someone who doesn't understand the technology side of the work.
You could also try e.g. BCG or McKinsey (quantum black) but the same will apply. The challenge is, it may be hard to turn it off and on, like you'll get assigned to fly to Minneapolis every week for 6 months, not just the occasional client visit. With the fancier (McKinsey) type firms you're more likely to get variety, but you'll travel every week
You could also consider looking at solutions architect type jobs. Especially at startups there may be some that let you go to client sites and do software work, but it will focus more on configuring for the client (at a startup that may still mean fresh coding). Some may be closer to just pre-sales, you'll have to ask a lot of questions in the interview