向来: "has always been / done [something]" (no change from the start)总是: "always is / does [something]" (refers to current state of affairs)
I think that this is good; however I think that 向来 does not emphasize so much the lack of change as the range of time beginning in the past. To stress the lack of change, I think you use 一向, 一直, or 一贯.
一向 stresses that that past behavior should be expected to remain unchanged in the present.
他一向很准时，一定会如约到达的。
He is always punctual, he will arrive as he promised.
一直 stresses the continuity of what is being described.
我一直在等你。
I've been waiting for you all the time.
我一直者想去看看长城。
I've always wanted to see the Great Wall.
一贯 stresses the consistency of the behavior.
我们一贯主张国家不分大小，一律平等。
We've always held that all nations, big or small, are equal.
向来 merely stresses that a behavior or situation has a history, not so much that there are no exceptions.
这两个民族之间向来可以通亲。
The two ethnicities have been intermarrying for a long time.
总是 seems to stress that a generalization is reliable and generally without exceptions.
她总是晚饭后出散步。
She always takes a walk outside after dinner.
老是 seems to stress that the situation matches an existing pattern of (usually negative) behavior.
你怎么老是这么晚回家？
Why do you always come home so late?
My examples are from nciku or various Pleco dictionaries. I should also add that many of these examples are overly precise in actual usage. In other words, various terms can and do often substitute for each other, but sometimes the difference in meaning is important to understand.