yeah the lair is untouchable by anybody but you as far as i can tell, so i guess it can feel a little bland sometimes.
I think it can turn into an awesome feature if it becomes more interactive.
currently I use it to hold the 'rest' of my army (i usually travel with 200 men, but have 100-200 more in there for use in sieges.) but more importantly as a prisoner holding pen, putting it next to whichever town i like best in whatever kingdom im currently a merc for in order to sell prisoners en mass whenever a ransom broker shows up.
I have toyed around with it using it as an ambush location before as well, running around with only companions near a dena landing and when a group chases me i run into my lair and jump em with 300+ men lol :p
I really hate dena pirates.