I really appreciate your input. Thank you.

I just got my first DSLR, a NIKON 3400D with 2 kit lenses, AF-P DX NIKKOR 18-55mm, f3.5 - 5.6G VR and AF-P DX NIKKOR 70 - 300 mm f4.5 - 6.3 ED. I am a novice and trying to learn as much as possible before my husband and I travel to Greece in Sept. for 2 1/2 weeks. We will be travelling lightly as we have several ports of call and don't want to get bogged down with too much to carry. I am planning on taking this camera as well as my Olympus TG4 point and shoot. My dilemma. I only want to take one lens with me for the DSLR. I will not have a tripod, but I want to take pictures of the beautiful scenery. There are some beautiful monasteries in the distance that I will want to take photos of as well as beautiful sunsets. I plan on taking tons of photos. Which lens would work the best for me? And if there is one that would work better for me, (not too expensive) what would that be? Is there anything other "must have" attachments I should take?