I cheat and have a full size table for a router in my shop..but a small one at times seems to be a better idea.
A fence is an important addition to a small table so you have something to ride against,for safety, and good control of the piece being cut,even using bearing bits.Having something for one end of what's being routed to rest against allows fingers farther away from bits,a sturdier holding method,less chatter,and just overall more control.Look online and see some ideas for fences.
I use a laminate top that has a pattern of 1/8" squares which is sweet for fine adjustments of a fence.Most of the time I can eyeball off the next line for accuracy for resetting the fence.
Some stopblocks that tighten to a fence..allow you better control for "start" and "stop" points for slots for bridges,etc.Sometimes simply drawing start/stop lines on the fence are enough to get by with some accuracy.
Of course,the heavier the table and the more solid it is,the less chatter and vibration for smoother cuts.
Adjusting a router is tough when it is in a table.Changing bits is also a problem.Some tables make it easier by using a removable panel the router is mounted to.The entire panel..say 6"x6" in a 12x12" table can be pulled out,adjustments made,and the panel popped back in place in the table after you are done.Making the panels of clear polycarbonite or lexan helps when you can see through it to change bits and make adjustments,especially when left in the table.
I think if I make a small table I'd incorporate all these features.Right now my table uses a 2hp old Makita in a full size reversible old table saw table(the entire top rolls over!),but it has an Incra Jig Ultra that eliminates that access without some serious removal of the fence system.it is a pain to adjust and change bits,but I manage and it is a sweet setup...basically why I haven't made a smaller one yet.I agree some jobs seem overkill with it....