I went Switzerland for my honeymoon recently, hope this helps.
I brought my tokina 1116, tamron1750 and a 50 f1.8. Most utilized are the first 2 mentioned.Initially I regretted not bringing my 18200, but I realised that I have only missed out that few percent of my total shots, which I could also do some cropping to achieve the same effect so the 0.5kg saved on the lens can be used to get more souvenir. Agree with some that u will be shooting urselves n landscapes most of the time so most likely wun need the Tele part.
If u r going to or v near to the mountains, the uwa will be v useful to capture the whole landscape. At open fields n top of mountains where the winds r so strong that your wife may not like to wait to set up the tripod, the uwa is useful for self portraits of both together. U shld be going in summer in 6mths time so this is unlikely to happen. Will be good to have a cpl filter to bring out the beautiful colours of the nature! If u r far from the mountains, the uwa may shrink ur mountain which the 1750 is more suitable in this case.
In cities or towns where there r tall buildings n lack of space to move backwards, the uwa is extremely useful. It will be advantageous to know how to compose with urselves in the uwa pics avoid faces distorted by the tokina. I see lots of distortion at every FL.
Depends on what u expect to shoot, ur budget and ur luggage space, but most importantly, enjoy great the time together.
So if u want to spend least for most effects, uwa + 50mm.
1 lens with sufficiently good convenience for landscape n portrait, good lowlight n bokeh, 1750.
1 lens with greatest convenience but compromise on image quality, 18200.