SOLIS (Synoptic Optical Long-term Investigations of the Sun) is a proposed suite of instruments that will modernize and greatly improve synoptic solar observations carried out by the National Solar Observatory on behalf the solar and solar-terrestrial physics communities. The primary scientific goal is to provide fundamental data necessary to understand the solar activity cycle, sudden energy releases in the solar atmosphere, and solar spectral irradiance changes. An operational goal is to produce real-time and near real-time data for forecasting space weather, and to augment the scientific yield from space mission such as SOHO and TRACE, and ground-based projects including RISE and GONG. State-of-the-art instrumentation and data collection techniques will be employed to enhance both the quality and quantity of data. A high degree of automation and remote control will provide faster user access to data and flexible interaction with the data-collection process. The instruments include a vector spectromagnetograph that will measure the magnetic field strength and direction over the full solar disk in 15 minutes, a full disk patrol delivering digital images in various spectral lines at a high cadence, a coronal emission line imager and photometer that will provide photometric and velocity images in at least five spectral lines, and a Sun-as-a-star precision spectrometer to measure changes in many spectral lines. The choice of sites for the instruments depends on potential partnerships with other observatories and the level of funding that can be obtained. The goal is to place the instruments at sites with large amounts of sunshine and coronal observing conditions as appropriate. The SOLIS proposal is currently under review by the National Science Foundation.