Proposals for health care cost containment emphasize high-value care as a way to control spending without compromising quality. When used in this context, 'value' refers to outcomes in relation to cost. To determine where health spending yields the most value, it is necessary to compare the benefits provided by different treatments. While many studies focus narrowly on health gains in assessing value, the notion of benefit is sometimes broadened to include overall quality of life. This paper explores the implications of using subjective quality of life measures for value assessment. This approach is claimed to be more respectful of patients and better capture the perspectival nature of quality of life. Even if this is correct, though, subjective measurement also raises challenging issues of interpersonal comparability when used to study health outcomes. Because such measures do not readily distinguish benefits due to medical interventions from benefits due to personal or other factors, they are not easily applied to the assessment of treatment value. I argue that when the outcome of interest in value assessment is broadened to include quality of life, the cost side of these measures should also be broadened. I show how one philosophical theory of well-being, Jason Raibley's "agential flourishing" theory, can be adapted for use in quality of life research to better fit the needs and aims of value assessment in health care. Finally, I briefly note some implications of this argument for debates about fairness in health care allocations.