Welcome aboard.
In the early stages of planning, having the whole of Europe at your fingertipsĀ can feel a bit overwhelming. It helps to narrow down your choices a bit, or at least pick a few location (not necessarily cities) that you 100% want to visit. This will help you build an itinerary.
There are some suggested itineraries here, but planning your own is a lot more rewarding. Bear in mind that southern Europe will be very hot at that time of year. If thatās not to your liking, consider a different time of year, or head further north.
https://www.interrail.eu/en/plan-your-trip/trip-ideas
I would suggest 2 days in one place is an absolute minimum (unless it really is just an enforced overnight stop). 3 or 4 is better (with the option to base yourself somewhere and do day trips),Ā because you lose a lot of time in the process of checking in & out of your hotel and moving to the next city. Be wary of āracking up countriesā just for the sake of it.
With 2 weeks I would choose to head either toward Spain & Portugal or towards Italy and maybe the Balkans. Not both. Compulsory reservations in France, Spain and ItalyĀ make Interrail a bit more of a hassle in those countries; a bit more so in Spain, a bit less so in Italy.
Iād also recommend reading this excellent guide to the passĀ https://www.seat61.com/how-to-use-an-interrail-pass.htmĀ and this guide to making the necessary seat reservationsĀ https://www.seat61.com/interrail-and-eurail-reservations.htm