Separately, optimization of takeoff, landing, and ground operations usually results in a slightly negative deck angle when taxiing.
Now I do notice, of two common types at London City, that the Embraer 170 has a quite noticeable nose-upward angle when on the ground, whereas the stretched Embraer 190 has a quite noticeable nose-downward tilt. Always intrigued me why this difference would be on two otherwise comparable types.
The Handley Page Hermes of 1950 had apparently such a nose-upward angle in the cruise that passing aircraft were known to enquire, presumably genuinely, if everything was alright. It was always accepted that it should have had a forward fuselage plug to balance it. Quite how the designers at Radlett got it so wrong (it was calculated to have notably impacted the fuel consumption) is not recorded. BOAC disposed of them prematurely after just a few years of service.