I am designing a PCB for a Numitron clock. It is just my own project, not for a company. The milling machine at school can only deal with 16mil+ sized traces, so I have some troubles routing traces between IC pins, for example. I must also note that I can only have 2 layer PCB's made at school. I have attempted to route the board several times now, but I always hit dead end, because something always crosses another trace. If I were to introduce vias, that would make things a lot easier, although the PCB would not look as nice, because I would have to connect it with wires externally.
My question is - are vias an acceptable solution, or is it a last resort? I imagine that in real life each via increases production cost, and that is a part of PCB design considerations, but what other pros and cons are there to vias?