There are thousands of types of spiders (technically arachnids and not insects) crawling around the U.S., but only two of them–the black widow and the brown recluse–can cause serious problems, and even those are rare. Most of the time you’ll see red bumps that hurt and itch if you’re bitten by a spider. Very few people get the severe pain and cramping of a widow bite or the decaying ulcers of a recluse bite (although if you do, get medical help right away).
When staying in a hotel, I check the bed before I bring the suitcase into the sleeping part of the room so that if I have to ask the manager for another room, then I haven't exposed my suitcase to the bugs. When settling in, I put my suitcase up on the suitcase stand or the desktop so that any bugs are less likely to crawl into it. An extreme measure would be putting the suitcase in the tub. If it's a porcelain tub, bed bugs would have a hard time crawling up it. It's also unlikely that they would randomly crawl up a tub, because it's not near the bed. But if I don't see bed bugs in the room when I inspect it, I just put my suitcase on the stand because I know the probability is really low that a bug is going to crawl up the stand and into my suitcase. I keep my clothes in the suitcase or hang them in the closet—I don't leave them on the floor because wandering bed bugs might crawl into them.
However, low-level infestations are also much more challenging to find and correctly identify. Other insects, such as carpet beetles, can be easily mistaken for bed bugs. If you misidentify a bed bug infestation, it gives the bugs more time to spread to other areas of the house or hitchhike a ride to someone else's house to start a new infestation. Learn about identifying bed bugs.

The size of bed bug bites varies with a number of different factors. Bed bugs inject an anti-coagulant along with their saliva when they pierce the skin to take a blood meal. This anti-coagulant is mostly responsible for how a person reacts to the bite and determines the size of the bug’s bite. Since people will have various sensitivities to the bed bug’s bite, the size of the bite will vary, as well. Another factor that influences the size of a bed bug reaction is the number of times a person is bitten. Bite reactions of people bitten many times are also variable, and their response may be either more or less intense as the number of bites increases.