A framework for requirements analysis is proposed that accounts for individual and personal goals and the effect of time and context on personal requirements. The implications of the framework on system architecture are considered as three implementation pathways: functional specifications, development of customisable features and automatic adaptation by the system. These pathways imply the need to analyse system architecture requirements. Different implementation pathways have cost-benefit implications for stakeholders, so cost-benefit analysis techniques are proposed to assess trade-offs between goals and implementation strategies. The use of the framework is illustrated with two case studies in assistive technology domains: e-mail and a personalised navigation system.