"Have sized up" is commonly used to mean evaluating or assessing a situation or person. Some synonyms that can be used in the same context are "appraise," "analyze," "estimate," "judge," "evaluate," "assess," and "scrutinize." These words convey the notion of careful observation and evaluation, with the aim of reaching a conclusion or making a decision. Other words that may be used in a similar context include "weigh," "consider," "survey," and "measure." Regardless of the words used, the general idea is to gather information and make an informed decision based on careful analysis and evaluation.