When you are charged with a crime and you decide to hire a criminal defense attorney, it is important that you and your attorney are on the same page. That is, you both have the same reasonable goals regarding the resolution of the case.
Defense attorneys are not magicians. We are educated and trained in the ways of criminal litigation. A good defense attorney should be a skilled negotiator and a talented trial attorney, but above all, a good defense attorney should have the foresight and experience to know what is a good and attainable outcome to your case.
You do not want a lawyer who will promise you the moon. And you should not expect the moon if the evidence is not in your favor.
If you are factually innocent and the evidence against you is particularly weak, it is reasonable to expect that your attorney should be able to get your charges dropped.
Now if you are factually guilty and the evidence against you is enough to convict, then you should expect your attorney to work toward a reasonable resolution, which may entail a plea bargain. Going to trial and expecting a not guilty verdict when the evidence against you is strong may be unreasonable.
What is a reasonable plea? If your charge is non-violent and you have never been in trouble before, Pretrial Diversion/Intervention or even probation with a withhold of adjudication is a reasonable resolution.
If you are a convicted felon and you are charged with a violent felony, then a jail or prison term may not be unreasonable if the evidence is sufficient to convict you. For instance, if you are a three-time felon charged with attempted second degree murder and have been enhanced as a Habitual Felony Offender, and the bottom of your guidelines recommends a minimum sentence of 76 months in state prison, a plea to anything less than 76 months may be considered reasonable.
It's all relative. It depends on what you are charged with, what your priors are, and above all, how strong the state's case is.
From my point of view, a healthy attorney-client relationship exists when both the attorney and the client have reasonable goals and expectations for the case. If a suppression motion is in order or the lack of evidence demands a jury trial, then so be it. But if a plea is a likely resolution, then the expectations as to what the plea should be must be reasonable.