Hi Carla -
<<"The reason I booked 4 days is because I had heard such good things about the area and there was a 4 day minimum stay at the place I rented.">>
Mürren is nice. I prefer Wengen:
<<" I really wanted to go to Zermatt so that we could see the Matterhorn it just seems like maybe I'm trying to squeeze too much in.
Lucas I read somewhere on this forum that you said you thought Titus was more interesting that Rigi so I was thinking maybe we would go with Titus in Lucerne instead of Rigi.">>
Titlis is the correct spelling.
We are now getting into subjective opinions and personal preferences.
In your case, they are guided by the fact that you have picked a poor time for outdoor activities in the higher alpine regions. It is really the disagreeable tail end of winter above 2000 meters. Trails are blocked by snow, sometimes even above 1500 meters, but the skiing is lousy. Snow slides from melting snow and lack of tourists (both hikers and skiers) and thus, customers, mean that they don't try to keep the trails open above 2000 meters. A lot of restaurants and hotels don't reopen from 'Spring" break until late June.
The famous Schilthorn and Jungfrau are accessible at that time by cograil or cableways. They will not be crowded.
The famous walk from Männlichen to Kleine Scheidegg (images attached)
opened on about June 16th in 2015 ( last time I was there in the Spring ( or maybe it was 2014) and there were banks of snow all around. I had my grandson with me, and we started along the trail, because the forecast said there might be a brief break in the clouds. There was...but the views were obscured by clouds above and below, and we walked a few hundred meters, then turned around, rode down to the Valley and went to Brienz. Sometimes you can be above a cloud deck, sometimes below, sometimes in one. The inside of a cloud is not very scenic. The weather comes in layers; altitude matters. Most people say, rightly so, do not make the expensive trip up to the Jungfrau if there are clouds around the top station. You can get detailed weather information for the region at your hotel, at the tourist offices, and at the train stations. In the high mountains, the weather can change quickly. Forecasts are not accurate much more than 24 to 48 hours in advance.
Further, I have a very strong personal opinion that when I have a brief time in Switzerland, I do not skip quality sights or activities just to save some money. Certainly, Switzerland is expensive. And, I try to avoid expensive lodging, and eat sandwiches for lunch....etc.
But, after you are back home, will you remember the special places more, or the money you saved?
Also, you have focused on high Alpine regions, at a time when Spring is pleasantly evident at lower altitudes, where there are also some special places.
So, I put all that together and say what I would do ...split your time with 2 or preferably 3 nights in Luzern and 3 or preferably 2 nights near the Jungfrau. Ordinarily, I prefer to stay as long a time as possible at one base, and even 5 days in Mürren or Wengen is fine, but not in early-mid June.
Luzern has some nice hikes at altitudes where the snow will be gone. (You'll see the German spelling with the "z" in that region. Pronounced the same either way). They don't have the dramatic high alpine scenery, and if you want to see that, by all means go to Titlis,or possibly the closer Pilatus, and spend more of your time in the Jungfrau region. Titlis is indeed nearby, but, if you have time in the high alps near the Jungfrau, and want to try something different but very Swiss, you might want to try the Rigi because there are some nice walks.
Check this thread:
and, this one, which has some nice pictures in it:
Others have been known to disagree, but I think that a boat ride on Lake Lucerne is the best in Switzerland, especially the the southern part of the lake illustrated in the link about the Swiss Path.
Luzern can be abase for a day trip even to eastern Switzerland, although I don't recommend it..
Those are my thoughts. Strictly my own personal preferences. If I wanted to spend all my time in the high Alps and have the best chance of good weather, I'd go in September. In fact, I plan to do that this year.