Whenever I start to plan something - especially a trip - my first resource is Google maps. It start with looking at where my destinations are in relation to one another right down to hotels & restaurants. As I have said many times we prefer to stay near the train station so I start on the map and search for hotels near the train station. I then start looking at them by clicking the names on the map and all of this lovely info comes up about them - then the best prospects I investigate further on several review sites and the hotels own website.
I do the same for restaurants, laundries, markets - what ever I need. It is also easy to get directions from where I am standing to where I want to be - even by public transport. I do double check the route on the transport site to be sure but most times Google does well.
I love the street view - it helps me pick out landmarks. If I come up from a subway it always takes a minute to decide which way to go but if I can locate a landmark and know to walk on X street towards X that makes a big difference. I will usually write directions to hotel from train station and review them on the train before arriving so I can walk out of station and head directly to my hotel. I will do that with subway routes that require several changes as well
line x towards X to X stop
change to line Y towards Y to Y stop
change to line Z to towards Z to Z stop
Simple directions on a post it note tucked into DH's pocket for referral as needed. This alleviates the "deer in the headlight" lost tourist look I see so many times.
A big part of my pre-trip planning is spent on the map getting to know the layout of my destinations and the various transport systems - what lines are near my hotel and what lines go to my destinations. I like to know where I am in a city in relation to hotel or other sites - being familiar with the map & city layout helps immensely.
I do keep mobile data on so I can stand in front of a restaurant and google it to see what the reviews say or at sites to get info when all of the descriptions are in the local language or just wander a city then pull up the map hit my hotel and get directions from where I am standing!