I can only personally speak to social experiences with regards to Monash university. With respect to unimelb I can only talk about other's experiences I have heard of from friends.
From your post, It seems like you want to avoid "snobbish" people. From my experience at Monash most be are quite good, friendly and only a small number of people are like that. Whilst I didn't study science at Monash I had a number of electives with students in that course and I had absolutely no problems with them. I found the vast majority of people who I interacted with were great people. I was able to make a number of friendships from those in Science even though I was studying a different course. This is just my experience so it may differ for others. For unimelb I don't know if the amount of "snobbish" people would be much different given both uni's are probably the same level of "prestige". Hopefully, someone at unimelb can give some proper insight into this.
I also think it is important to understand that there is a whole different way of how people interact with each other at university compared to highschool. In high school, a lot of friendships are kind of forced for the sake of it given you spend so much time together. Also cliques in highschool form quite quickly and it becomes harder to make new friends later on. I can see how moving to a new school may exacerbate all these factors.
At university, students are a lot more open to making new friends and interacting with those outside their existing social circles.
As cliche as it the notion that you only get out as much as you put in is true. If you want to go to university purely for studying, only going for lectures, tutes, practicals and leaving as soon as you are done it is going to be difficult to make friendships. If you stay at university outside of class and study, have lunch, join clubs, play sport with others you are more likely going to be able to develop friendships.
EDIT:
wanted to add a little bit on the 1 hour vs 2 hour travel. I think travel for university is quite significant. Going to and from university would be 2 extra hours for Monash. Over a week that maybe 8 extra hours (but you could possibly cut this down if you are happy watching lectures from home and stacking your timetable on certain days). If you are able to study or do something productive whilst travelling this may not be a problem to you but for some all that travel can get quite exhausting.